Category: CBSE

CBSE Previous Year Solved  Papers Class 12 Maths Delhi 2014

Time allowed: 3 hours                                                                                          Maximum Marks : 100
General Instructions:

1. All questions are compulsory.
2. Please check that this question paper contains 26 questions.
3. Questions 1-6 in Section A are very short-answer type questions carrying 1 mark each.
4. Questions 7-19 in Section B are long-answer I type questions carrying 4 marks each.
5. Questions 20-26 in Section C are long-answer II type questions carrying 6 marks each.
6. Please write down the serial number of the question before attempting it.

SET I

Note: Except for the following questions, All the remaining question have been asked in previous Sets.

SECTION – A

SECTION – B

SECTION – C

23. Two schools P and Q want to award their selected students on the values of Discipline, Politeness and Punctually. The school P wants to award Rs x each, y each and Rs z each for the three respective values to its 3,2 and 1 students with a total award money of Rs 1,000. School Q wants to spend Rs 1,500 to award its 4,1 and 3 students on the respective values (by giving the same award money for the three values as before). If the total amount of awards for one prize on each value is Rs 600, using matrices, find the award money for each value. Apart from the above three values, suggest one more value for awards.
Solution: Let the awards for Discipline, Politeness and Punctuality be Rs x, Rs y and Rs z respectively.

28. A dealer in rual area wishes to purchase a number of sewing machines. He has only Rs 5,760 to invest and has space for at most 20 items for storage. An electronic sewing machine cost him Rs 360 and a manually operated sewing machine Rs 240. He can sell an electronic sewing machine at a profit of Rs 22 and a manually operated sewing machine at a profit of Rs 18. Assuming that he can sell all the items that he can buy, how should he invest his money in order to maximize his profit ? Make it as a LPP and solve it graphically.

29. A card from a pack of 52 playing cards is lost. From the remaining cards of the pack three cards are drawn at random (without replacement) and are found to be all spades. Find the probability of the lost card being a . spade. [6]



OR
From a lot of 15 bulbs which include 5 defectives, a sample of 4 bulbs is drawn one by one with replacement. Find the probability distribution of number of defective bulbs. Hence find the mean of the distribution. ,
Solution: Let D be the event of drawing a defective bulb and X denote the variable showing the number of defective bulbs in 4 draws. Then
P(D)=5/15

SET II

Note: Except for the following questions, All the remaining question have been asked in previous Set.

SECTION – A

SECTION-B

19. Prove the following using properties of determinants:

SECTION – C

SET III

Note: Except for the following questions, AH the remaining question have been asked in previous Sets.

SECTION – A

SECTION -B

19. Using properties of determinants, prove the following:

SECTION – C

CBSE previous Year Solved  Papers  Class 12 English Outside Delhi 2010

Time allowed : 3 hours                                                                                           Maximum Marks: 100
General Instructions :

1. This paper is divided into three sections : A, B and C. All the sections are compulsory.
2. Separate instructions are given with each section and question, wherever necessary. Read these instructions very carefully and follow them faithfully.
3. Do not exceed the prescribed word limit while answering the questions.

SET I

SECTION —A
(READING)

Question.1. Read the passage given below and answer the questions that follow:

1.  Today’s woman is a highly self-directed person, alive to the sense of her dignity and the importance of her functions in the private domestic domain and the public domain of the world of work. Women are rational in approach, careful in handling situations and want to do things as best as possible. The Fourth World Conference of Women, held in Beijing in September 1995, had emphasized that no enduring solution of society’s most threatening social, economic and political problems could be found without the participation and empowerment of the women. The 1995, World Summit for Social Development had also emphasized the pivotal role of women in eradicating poverty and mending the social fabric.
2.  The Constitution of India had conferred on women equal rights and opportunities – political, social, educational and of employment – with men. Because of the oppressive traditions, superstitions, exploitation and corruption, a majority of women are not allowed to enjoy the rights and opportunities, bestowed on them. One of the major reasons for this state of affairs is the lack of literacy and awareness among women. Education is the main instrument through which we can narrow down, the prevailing inequality and accelerate the process of economic and political change in the status of women. ‘
3.  The role of women in a society is very important. Women’s education is the key to a better life in the future. A recent World Bank study says that educating girls is not a charity, it is good economics and if developing nations are to eradicate poverty, they must educate the girls. The report says, that the economic and social returns on investments in education of the girls considerably affect the Human Development Index of the nation. Society would progress only if the status of women is respected and the presence of an educated woman in the family would ensure education of the family itself. Education and empowerment of women are closely related.
4. Women’s education has not received due care and attention from the planners and policy makers. The National Commission for women has rightly pointed out that even after 50 years of Independence, women continue to be treated as .the single-largest group of backward citizens of India. The role of women in overall development has not been fully understood nor has it been given its full weight
   in the struggle to eliminate poverty, hunger, injustice and inequality at the national level. Even, when we are at the threshold of the 21st century, our society still discriminates against women in matters of their rights and privileges and prevents them from participating in the process of national and societal progress. Various committees and commissions have been constituted before and after Independence to evaluate the progress in women’s education and to suggest ways and means to enhance the status of women. The female literacy rate has gone up in the 20th century from 0.6 percent in 1901 to 39.29 percent in 1991 but India still possesses the largest number of illiterate women in the world. The Female Literacy Index for the year 1991 shows that there are eight states which fall below the national average. The most populous states of the country, UP, MP, Bihar and Rajasthan fall in the category of most backward states as far as female literacy is concerned. .
5.  The prevailing cultural norms of gender behaviour and . the perceived domestic and reproductive roles of women tend to affect the education of the.girls. Negative attitude towards sending girls to schools, restrictions on their mobility, early marriage, poverty and illiteracy of parents affect the girls’ participation in education.
6.  Women’s political empowerment got a big boost with the Panchayati Raj Act of 1993 which gave them 30 percent reservation in Village Panchayats, Block samities and Zila Parishads throughout the country. The National Commission for women was also set up in 1992, to act as a lobby for women’s issues.
7.  The educational system is the only institution which can counteract the deep foundations of inequality of sexes that are built in the minds of people through the socialisation process. Education, is the most important instrument of human resource development. Educational system should be used to revolution is  the traditional attitudes and inculcate new values of equality.

(a) (i) Mention any two attributes of a modem woman.
Answer : (i) Women are careful in handling situations.
(ii) They are rational in their approach.
(ii) Why is women’s participation and empowerment
considered necessary ?
Answer : Society’s most threatening social, economic and political problem’s solution could not be found without the participation and empowerment of women.
(iii) Which factors adversely affect the education of
girls ?
Answer : The prevailing cultural norms of gender bias ness and the perceived domestic and reproductive roles of women tend to affect the education of the girls.
(iv) What benefits did the women get with the enactment of the Panchayat Raj Act of 1993 ?
Answer: The women got 30% reservation in village Panchayats, Block samities and Zila parishads, throughout the country with the enactment of the Panchayat Raj Act of 1993.
(v) By what process can we remove the sense of inequality of sexes from the minds of the people ?
Answer : The educational system is the only institution which can remove the sense of inequality of sexes from the minds of the people through the socialisation process.
(b) Pick out words from the passage which mean the same as each of the following:
(i) Gruel and unfair (para 2)
Answer: oppressive
(ii) Remove (para 3)
Answer: eradicate
(iii) full of people (para 4)
Answer: populous

Question.2. Read the passage given below and answer the questions that follow:
Despite all the research, each one of us catches cold and most of us catch it frequently. Our failure to control one of the commonest of all ailments, sometimes seems ridiculous. Medical Science regularly practices transplant surgery and has rid many a countries of such killing diseases as Typhus and the Plague. But the problem of common cold, is unusually difficult and much is yet to be done to solve it.
It is known that a cold is caused by one of a number of viral infections that affect the lining of the nose and other passage leading to the lungs but the confusing variety of viruses makes study and remedy very difficult. It was shown in 1960 that many typical colds in adults are caused by one or the other of a family of viruses known as rhinoviruses, yet there still remain many colds for which no virus has yet been isolated. There is also the difficulty that because they are so much smaller, than the bacteria, which causes many other infections, viruses cannot be seen with ordinary microscopes. Nor can they be cultivated easily in the bacteriologists laboratory, since they only grow within the living cells of animals or plants. An important recent step forward, however, is the development of the technique of tissue culture, in which bits of animal tissue are enabled and to multiply independently of the body. This has greatly aided virus research and has led to the discovery of a large number of viruses. Their ^existence had previously been not only unknown but even unsuspected. .
The fact that we can catch cold repeatedly creates another difficulty. Usually a virus strikes only once and leaves the victim immune to further attacks. Still we do not gain immunity from colds. Why ? It may possibly be due to the
fact that while other viruses get into the bloodstream where antibodies can oppose them — the viruses causing cold attack cells only on the surface. Or it may be that immunity from one of the many different viruses does not guarantee protection from all others. It seems, therefore, that we are likely to have to suffer colds for some time yet.
(a) On the basis of your reading of the above passage, make notes on it in points only, using abbreviations wherever necessary. Also suggest a suitable title.
Answer:
Title: Difficulties of Common Cold.
1. Notes
(i) Common cold
(a) everyone catches
(b) Med Sc. failed to control
(c) much has to be done in order to cure it.
(ii)causes
(a) viral infections
(b) variety of viruses
(c) family virus known as Rhino.
(iii)other problems
(a) too small to be seen under microscp
(b) leaves victim immune to further attacks
(c) can’t be cured by anti bods.

(b) Write a summary of the above passage in about 80 words using the notes made.

SUMMARY

Everyone catches cold and the cure of it has not been found yet. Medical Science has failed to control it. It is caused by viral infections that affect the lining of the nose and other passages. The confusing variety of viruses, makes the study difficult. Family virus rhinovirus is also responsible for it. The viruses are so small that they can neither be seen with microscope nor cultivated in laboratory. This virus leaves the. victim immune to further attacks. They do not get into the bloodstream where antibodies can oppose them. Therefore, we have to suffer from cold for some time yet.

SECTION – B
(ADVANCED WRITING SKILLS)

Question.3. You are the Secretary of your School Literary Association. Write a notice in not more than 50 words for your school notice board, giving details of the proposed inauguration of the Literary Association of your school. You are ‘XYZ’ of Jain Vidyashram, Cuddalore. 
OR
You are the General Manager of E.V.L. Company which requires posh bungalows on company lease, as guest houses. Draft an advertisement in not more than 50 words under classified columns to be published in “The New Indian Express”1.
Answer:

OR

Question.4.Your school organized an exhibition-cum-sale of the items prepared under Work Experience by your school students. There was an overwhelming response from the public. Prepare a report in 100-125 words for a local daily. You are the Co-ordinator, S.U.P.W activities, Nita School, Gurgaon.
OR
Your school organized a seminar on Swine Flu for creating awareness among students of your school, and then- parents. As Secretary of the Health Club of Oasis Public School, Hyderabad, write a report in 100-125 words for ‘The Deccan Herald’.
Answer:
Exhibition-Cum-Sale
Report: Co-Ordinator (S.U.PW. Activities)
Nita School, Gurgaon
12th February, 20XX .
An Exhibition Cum Sale of the items prepared by students of our school under Work Experience was organized in the school premises on 3rd and 4th February. The exhibition was inaugurated by honorable Principal, Mr. N.M. Pareek. Parents as well as public were cordinally invited to watch the efforts of the children. Students showed their skills with exuberance. The items made by the students included models and products made with discarded material which has some utility. As the name itself suggests, Socially Useful Productive Work, the exhibition proved to be truly useful and the sale was also high. The exhibition showcased the creativity and talents of the students’ right from the junior section to the senior ones. It was applauded by one and all. The effort of the students was commendable and the response from the public was overwhelming which encouraged more and more students to be a part of S.U.P.W.
OR
A Seminar on Swine Flu
Report: Secretary (Health Club)
Oasis Public School, Hyderabad
25th March, 20XX
A seminar on ‘Swine Flu’ was organized on 20th March, 20XX in Oasis Public School, Hyderabad to create awareness among students and their parents. School chairman Mr. L.N. Sharma was the chief guest. In his welcome speech, he told that swine influenza, is a contagious respiratory disease that normally effects pigs but has harmful effects on human beings also, if they come in contact with infected pigs. The seminar was attended by several eminent doctors and medical officers who suggested ways to cure this disease. Students from “* other schools were also invited to present their views on the symptoms of the Flu and the precautions to be taken. It was told by the doctors, that although the vaccines for swine flu are available in medical stores but if not cured in time, it may • prove to be fatal. The parents found this seminar extremely beneficial as they also became aware of the causes and cures of this disease. A team of medical experts told that it is just like seasonal flu and can be reduced by maintaining good hygiene.

Question.5.Write a letter to the Editor, ‘The Hindu’, Chennai about rash and reckless driving by the people in your city, suggesting preventive measures. You are Kamal/Kanwar of 10, Mount Road, Velacherry.
OR
You have shifted your residence froih 10, Lajpat Road to House No. 232, Aurobindo Marg, Delhi. Write a letter to the General Manager, MTNL, requesting him for an early transfer of your telephone line. You are Rohit /Radhika of 15, The Mall, Amritsar.
Answer:
10, Mount Road,
Velacherry 10th April, 20XX
The Editor The Hindu
Chennai
Subject: Rash and Reckless driving
Dear Sir,
Through the columns of your esteemed newspaper, I would like to share my views on the increasing cases of rash and reckless driving in the city. This has created havoc in the city as it has become a routine habit of the people to drive at a very fast speed even in the colonies which results into one or two cases of accidents. Due to the negligence of the people, sometimes small children playing in the lanes become victims. The people who are responsible for these accidents are generally teenagers who are given bikes by their parents or they borrow it from their friends tp show off. I have noticed many times that they do stunts on the busy roads which is not only risky for others’ lives but their lives too. Number of accidents have been increasing daily which sometimes results in the loss of life. This should be controlled and traffic police should take strict action against it. Teenagers should not be given the permission to drive until they are perfecdy trained to drive on the roads. If the driver is found, the registration of the vehicle should be cancelled or the driving license should be seized.
Hope this letter would leave an impact on the public. Thanking you Yours Sincerely,
Kamal (A resident)
OR
Answer:
15, The Mall Amritsar .
18th June, 20XX
The General Manager MTNL •
Subject: Early transfer of telephone line
Dear Sir,
This is to inform you that I, Radhika of 15, The Mall, Amritsar, have shifted my residence from 10, Lajpat Road to House No. 232, Aurobindo Marg, Delhi for a minimum period of three years. You know that Delhi is a vast city and the distances are too much that it is impossible to reach
anywhere within a short time. In such a situation the only means of communication left with us is the telephone. But getting the telephone line transferred immediately after shifting will take a lot of time. So I request you for an early transfer of telephone line to avoid any inconvenience. I am submitting all the papers required for the transfer of line. Thanking You Yours Sincerely,
Radhika

Question.6. As compared to the older generation the youth of today are gteady inclined to pursue adventurous activities either for money or for fun. There is a latest craze for joining reality shows, rafting, rock climbing, mountaineering etc. Write an article in 150-200 words on which life would you prefer- safe or adventurous.
OR
Science attempts to explore the secrets of nature while religion wants to reveal the very purpose of existence. The aim of both Science and Religion is to discover the truth. Write an article in 150-200 words on ‘Science and Religion’.
Answer:
‘Which Life Would You Prefer—Safe or Adventurous ?’
Adventurous life has attracted youth a lot and it has become the fastest growing charm. It result due to either fun or money. That is why adventure tourism has grown in decades. Adventure life excites and rejuvenates a man; so more and more youth are fascinated by it. Experiencing the life in the lap of nature rock climbing, river rafting, jungle safari, mountaineering, skiing etc. is totally a different experience. Now-a-day’s adventure tour operators are flourishing only because of the increasing popularity of adventurous trips by people. They enjoy new experience and seek out thrills, but, it involves risk equally. These activities signify danger and attract people who are ready to gamble their personal safety. They risk their life in search of a rush of excitement or an unusual accomplishment. The reality shows have also prompted our youth to take part in risky adventurous games by promising fabulous prizes and stardom. Some people try these stunts at home putting their life in extreme danger. It is impossible to understand why people engage in such activities.
OR
Science And Religion
Science and Religion, we can say are the two sides of a coin. The relationship between Science and Religion has been a subject of study since ages. It has been a subject of conflict and harmony among different regions, cultures and Historians. Both science and religion pursue knowledge of the universe and search truth using different7 methods. The only difference is that Science needs reasons and evidence whereas Religion relies on faith and revelation. Although Scientific innovations are all based on the religious findings, they claim which to be their own researches. Science tries to find the secrets of nature while Religion tells the reason of our existence. Religion is based upon trust quite away from the arguments presented by Science. That is why they are termed as two sides to a coin. Scientific facts may be influenced by religion but many people reject this idea. Religion stands upon tradition whereas science is factual but the objectives of both Science and Religion is human welfare. In fact, both are complementary to each other

SECTION – C
(TEXT BOOK)

Question.7. Read the extract given below and answer the questions that follow:
… on their slag heap, these children
Wear skins peeped through by bones and spectacles of steel
With mended glass, like bottle bits on stones.
All of their time and space are foggy slum So blot their maps with slums as big as doom.
(a) Which two images are used to describe these slums ?
Answer : The two images used to describe these slums are :
(i) Foggy slums
(ii) Slums as big as’deom.
(b) What sort of life do these children lead ?
Answer : These children lead a miserable life confined to their dark and damp slums. Their childhood is lost on slag and heaps of garbage.
(c) Which figure of speech is used in the last line ?
Answer: Simile

Question.8. Answer any three of the following in 30-40 words each :
(a) What is the significance of the parting words of the poetess and her smile in ‘My Mother at Sixty-Six’ ?
Answer: ‘The parting words’…. See you soon Amma’ means that the poetess is doubtful about meeting her mother again as she is frail and too old.
(b) According to the poet, what is it that human beings can learn from nature ? (Keeping Quiet)
Answer : Human beings can learn to construct rather than destruct, from nature. It teaches us the art of preserving life, beneath the apparent dark surfaces, there is life.
(c) What makes human beings love life in spite of troubles and sufferings ? (A Thing of Beauty)
Answer : The beauty of nature, rivers, mountains, fresh air, flowers, the sun, the moon, the green pastures and all beautiful things make human beings love life.
(d) What will happen to Aunt Jennifer’s tigers when she is dead ?
Answer : The tigers created by Aunt Jennifer will keep on prancing in the panel after her death!

Question.9. Answer the following in 30-40 words each :
(a) What changes came over little Franz after he heard M. Hamel’s announcement ? (The Last Lesson)
Answer : When Franz came to know about M. Hamel’s announcement, he was shocked. He felt sad and regretted for not being attentive in the class and serious about his studies.
(b) Why does the author say that the Bangle makers are caught in a vicious web ? (Lost Spring)
Answer : The Bangle makers are said to be caught in a vicious web because they are exploited by sahukars, middlemen, policemen, bureaucrats and politicians. They are not able to make their co-operative societies for their benefit.
(c) Why was Edla happy to see the gift left by the peddler ? (The Rattrap)
Answer:When Edla heard about the theft at the Crofters house, she became sad. On reaching home she discovered that the peddler had not taken anything from her house and left a small rattrap as a gift and three, ten stolen kronors, because of which she became extremely happy.
(d) Why did Sophie like her brother Geoff more than any other person ?
Answer : Sophie liked her brother Geoff more than any other person because he was the only one who took interest in her imaginary wild stories. Moreover, he never revealed her secret to anyone and being a motor mechanic, she used to roam with him everywhere.

Question.10. Answer the following in 125-150 words :
“… there was terror in my heart at the overpowering force of the waves”. When did Douglas start fearing water ? “Which experience had further strengthened its hold on his mind and personality ?
Answer: Douglas’ first experience of water was horrific. He was with his father on a beach in California when a strong wave swept him over and terrified him completely. So Douglas was eleven years old when he started learning swimming in Y.M.C.A. pool. It was safe, as its depth at the end was only two feet. However the further end was nine feet deep. One day he was sitting alone on the edge of the pool when a strong young man threw him into the deep end of the pool for fun. He was nearly drowned. He could not come out of water and thus left the idea of swimming. The fear of water persisted with him for many years.
Then he decided to overcome his fear of water because he could no more enjoy water sports like canoeing, boating, swimming, etc. Moreover, he could not enjoy river bath. He had faith in the words spoken by Roosevelt, “All we have to fear is the fear itself”, .which gave him strength. He hired
an instructor to learn swimming. The instructor put all his efforts to turn him into a good swimmer.

Question.11. Answer the following in 125-150 words :
Why did Mr. Lamb try to give courage and confidence to Derry ?
Answer : Derry and Mr. Lamb shared the same problem of loneliness as they were physically disabled. They both lived a secluded life. Mr. Lamb had an Apple garden and he kept his gates always open. When Derry came to his garden, he welcomed him. He found a companion in him as Derry was too suffering the same pain as Mr. Lamb was. Mr. Lamb was disabled but was calm and maintained peace with people around him and he infused the same feeling in Derry. He encouraged Derry . also to face his disability boldly. Before coming in contact with Mr. Lamb, Derry felt lonely due to the behaviour of the people- but Lamb inspired him and filled him with self-confidence and determination. He taught him to move ahead in life as his brain and senses were working fully. He imbibed positive thinking in him and developed a kind of sympathy with him, thus showing him the way to live in this world in spite of his disability.

Question.12. Answer the following in 30-40 words each :
(a) What did the British Officer’s Secretary tell the Maharaja ? Why did the Maharaja refuse permission ?
Answer : The British Officers Secretary revealed his desire to kill the tigers but the Maharaja refused the permission as according, to an astrologer, his death would be caused by a tiger and if he allowed him to kill the tiger, the number of tigers would be reduced.
(b) Why did the messenger come to Dr. Sadao ? What did
Hana think about it ?
Answer : Since The General was extremely ill and would require 2011 Dr. Sadao’s service any moment for an operation, therefore a messenger was sent to call him. When he came to his house, Hana thought that he had come to arrest him on account of giving shelter to an enemy.
(c) Why did Evans not take off his hat when Jackson ordered him to do so ?
Answer : Evans had curly hair but he had shaved his head to remain in disguise. So he did not take off his hat when Jackson ordered him to do so. Instead he told Jackson that, the hat was lucky for him.
(d) Why was Zitkala-Sa terrified when Judewin told her that her hair would be cut short ?
Answer : Zitkala-Sa was terrified when Judewin told her that her hair would be cut short because in her community, keeping long hair was the symbol of bravery and only those warriors who were punished, had their hair shingled.

SET II

Note : Except for the following questions, all the remaining questions have been asked in previous sets.

SECTION – B
(ADVANCED WRITING SKILLS)

Question.5. Write a letter to the Secretary, Youth Hostels, Jaipur, requesting him to provide accommodation for 3 days to 4 members of your family going on a tour of Rajasthan. You are Kamini / Kamlesh, Gandhinagar, Chennai.
Answer:
Gandhinagar,
Chennai
20th June, 20XX
The Secretary
Youth Hostel, Jaipur
Subject: Accommodation for 4 members for three days
Dear Sir,
This is to inform you that a tour to Rajasthan has been planned by my family. You, are requested to arrange for an accommodation for four members for three days in your hostel. Kindly arrange for; food also. As it’s a new place for
us, we would be obliged if you could arrange a taxi from 10 a.m. to 5.p.m. at reasonable rates. Please ensure that the cab driver has been registered with the government authority and should be honest as we come across few cases of unscrupulous ways of drivers on a daily basis.
Payment will be done only after checking out and it will be according to your terms and conditions provided that all the facilities will be given to us on time.
Thanking You Yours Sincerely,
Kamini

Question.6.It is due to cable television that programmes are brought to our homes day and night for all the seven days in a week. It has brought a lot of change in the lifestyle of the people. Write an article in 150-200 words on ‘Cable TV-A Boon or A Bane’.
OR
India is standing at the threshold of joining the developed nations but that is not possible till we achieve complete literacy in the country. The contribution of students may be very significant in achieving our goals. Write an article in 150-200 words on “The Role of the Students in Removing Illiteracy”.
Answer:
‘Cable TV-A Boon or A Bane’
On an average, a person spends 40% of his time watching TV. In the last two decades, television has become the most powerful means of entertainment. On top of it, cable TV has brought a revolution in the lifestyle of people. The cable TV has invaded our rooms and we have become addicted to it. In case there is power failure or fault in cable, we feel paralyzed and it seems as if something is missing from our daily routine.
Nobody, has remained unaffected by its influence, be it children or the aged. From films to cartoons, news channels to sports channels, serials to music channels, every channel has its unlimited viewers. Advertisements have their own positive as well as negative effects both on youth and elders. Many times we shirk away our important work for the sake of watching a movie or a daily soap. There is repeated telecast also of the programs and that is not only once, but twice or thrice. Our outdoor activities, reading habits, social life has also not remained unaffected by watching TV. We prefer staying at home, confined to our rooms, watching television instead of going out. That is why it is called the “Idiot Box”. We should find better alternatives like going for picnic, playing outdoor games, visiting relatives etc. instead of merely watching television.
OR
The Role of the Students
in Removing Illiteracy
Any country’s progress depends on its youth. One cannot deny their importance in building and upliftment of a nation. They play a vital role in the development of a country. It is a known fact that in India, there are mostly villages, and the people living in these villages are mostly illiterate. They don’t even know to write their names and recognition of letters is far beyond from their reach. So it, becomes the duty of the youth to dedicate their services to teach the, illiterate but also the most important community of our country. The villagers are bound by the superstitions and it is necessary to remove these beliefs from their minds. The students are the only ones who can change their mindset and transform them. They can easily teach them after their school hours and tell them the new techniques which would be helpful in their farming process. The students should divide themselves in groups of four or five and start giving evening classes to the illiterate people of their respective areas. With the increase in the population, the responsibilities of students have also increased. Their role is full of challenges and they, can only bring revolutionary changes in making India a progressive and prosperous country.

SECTION – C
(TEXT BOOK)

Question.12. Answer the following in 30-40 words each :
(a) Why do you think, was the Maharaja in danger of losing his throne ?
Answer : According, to an astrologer’s prediction, the Maharaja started to kill tigers, but when a high ranked British Official wished to hunt tigers, the Maharaja did not allow him and even refused to get him photographed near the carcass of tiger. Thus, he was in danger of losing his kingdom.
(b) What forced Dr. Sadao to be impatient and irritated with his patient ?
Answer : Dr. Sadao was sheltering an enemy by putting his position and life in high risk. This secret was soon aired and he became worried. Therefore he thought of a plan to get rid of his patient.

SET III

Note : Except for the following questions, all the remaining questions have been asked in previous sets.

SECTION – B
(ADVANCED WRITING SKILLS)

Question.5.There is a flood of advertisements on television channels these days. Useless commodities and even superstitious beliefs are promoted through glamorous and exaggerated* presentations. Write a letter to the Editor, ‘New Indian Express’ about the negative influence such advertisements have on the minds of the people. You are Radha/Ramesh of MayurVihar, Lucknow.
OR
Write a letter to the Manager, Haldirams, Nagpur, requesting him to supply 60 lunch packets for your excursion party which would be travelling by G.T. Express from Delhi to Chennai. Your train would reach Nagpur at 12.15 p.m. Mention your coach number and the other relevant details. You are Priti/Pritam, Co-ordinator of the Excursion Party of Sriram Vidya Niketan, Delhi.
Answer:
Mayur Vihar,
Lucknow
23rd October, 20XX
The Editor
New Indian Express
Subject: Negative Influence of Advertisements .
Dear Sir,
Through the esteemed columns of your newspaper, I would like to bring to your notice the influence that the advertisements have on the minds of the public. The aim of the advertisements is to present a commodity in the best way and promote its selling. This dramatization is done by the celebrities from the field of film line, sports etc. They have positive and negative impact both, on our minds. But most of time these ads lure people by representing their product , falsely. Based on the images of fairness creams, women often feel attracted towards them and they spend a lot of money buying them. These ads communicate false images of men also which are unrealistic. So, these ads should not be promoted and action should be taken against the companies for promoting their false product.
Hope my letter would drive a positive response.
Thanking You Yours Sincerely,
Radha (Mayur Vihar)
OR
Sriram Vidya Niketan
Delhi ,
14th April, 20XX The Manager Haldirams, Nagpur
Subject: Supply of 60 lunch packets for excursion party.
Dear Sir,
This is to inform you that an excursion party to Chennai is being organized for 60 members. These people will be travelling by G.T. Express from Delhi to Chennai via Nagpur. The train will reach Nagpur station at 12.15 p.m. and stop for about half an hour. The party will be requiring lunch there as after that the train will not halt at any big station.
Therefore, I request you to arrange for 60 lunch packets for the party. It must include Chapati, dal, mix vegetable, rice and fresh salad. Please do not pack raita as there are chances of spilling. I hope that all the items would be fresh and as per our requirement. Kindly ensure that the packets should reach coach No. S-7. You are requested to be ready with packets at platform No. 1 before the arrival of the train. Payment will be done only after getting the packets.
Thanking you Yours Sincerely,
Pritam
(Co-ordinator, Sriram Vidya Niketan)

Question.6. The other day you visited the grain market at Azamgarh. There you saw sacks of wheat being carried in over loaded * bullock carts by emaciated oxen. You felt disturbed by the cruelty meted out to harmless animals. Write an article in 150-200 words suggesting ways to prevent cruelty towards animals.
OR
Compulsory value-based education is the only remedy for inculcating values among the future citizens of the country. This will also help in the prevention of crime in the country. Write an article in 150-200 words on the needs of compulsory value-based education.
Answer:
Cruelty to Animals
The sight I saw in the grain market was really heart rending. The sacks of wheat were being carried in over loaded bullock carts and the lean and weak oxen hanged in the air as it is was lifted up by the overloaded cart. The ‘PETA’, i.e. People for Ethical Treatment of Animals get awards daily but in reality the situation is entirely different. The prevention of cruelty to animals appears only in news. In fact, the innocent animals are ill-treated and neglected every day. Nobody, cares about the agony of the animals. On a daily basis we come across a sight or two where the horses, donkeys, camels, oxen, etc. are subjected to utter cruelty by heartless human beings.
The owners overload the carts carrying goods and the police turn their eyes blind by taking bribes or on the pretext that the tradesman is poor. I don’t understand why these people refuse to see that the animals cannot narrate their sufferings but they do feel. They have equal right on earth as we have.
It’s high time, to realize that we have a responsibility towards these meek creatures of God which demand our care and love too.
OR
Value Education—The need of the HourIn this fast changing and competitive world, the values and ethics are deteriorating. The moral dilemmas andconflicting values have become too common. Therefore, it is necessary to ensure a curriculum which enables a child to revive his lost values and think and feel right. Only then, a stable and morally integrated future generation will be developed. This can be done through value education which has rightly been projected as a national priority in the National Educational Policy. The children can thus attain self-esteem, dignity and enhance their ability to decide between the good, and bad, right and wrong. Till now the whole emphasis is on academic progress but now it’s time for value education to find its place in the curriculum. The field of value education is as vast as life itself. It touches every aspect of human life and personality. There is sharp decline in the moral standards of the people due to diplomatic attitude and changing interests. The situation is alarming as the ethics and values are in a state of constant flux and this is leading to deterioration of civic sense as well as the country. The main aim of people is only the accumulation of money by any  means for which the crime graph is consistently rising high. They have forgotten their moral duties and consideration for  the fellowmen. Thus, value education should be taught in the  schools on a regular.

SECTION – C
(TEXT BOOK)

Question.8. Answer any three of the following in 30-40 words each :
(d) Why do you think Aunt Jennifer created animals that are so different from her own character ?
Answer : Aunt Jennifer had experienced constraints in her married life. The ring around her finger symbolizes, the weights of her marriage so she created tigers which are representative of the freedom that she aspires for.

Question.9.Answer the following in 30-40 words each :
(e) What did Sophie tell Geoff about her meeting with Danny Casey ?
Answer : Sophie told her brother Geoff that she had met Danny Casey in the arcade and that he was not very tall. He had green eyes and was gentle.

12. Answer the following in 30-40 words each:
(a) What led the Maharaja to start out on a tiger hunt ?
Answer : The Maharaja was told by an astrologer that a tiger would become the cause of his death at the time his birth born. So, he began his tiger hunt as soon as he was entitled to the throne.
(b) In what context does Hana remember General Takima ? What does she infer ?
Answer : Dr. Sadao was sheltering a prisoner of war from .U.S.A., the country with which they were involved in a war. They were always in terror of getting labelled with the tag of terrorist. Thus, she remembered the General in the content that he would support-them in case of any questioning by the authority.

 

CBSE Notes for Class 8 Computer in Action – Introduction to Visual Basic

Adobe Photoshop CC 2015 is one of the most powerful image editing and creation software. We can use this software to correct errors in photographs, to add effects to images or to build complex images from scratch. This software is widely used for creating graphics for magazines, newspapers and websites. We can improve or change colours of faded photographs; add, remove or replace people from photographs; and apply artistic effects to our photographs using this software.
Let us get started to learn about this exciting and versatile software program.

Learning Objectives

To Learn about:

❖ starting Adobe Photoshop CC 2015.
❖ components of Photoshop workspace.
❖ selection tools in Photoshop.
❖ drawing tools in Photoshop.
❖ painting tools in Photoshop.

STARTING PHOTOSHOP
To open Adobe Photoshop,
Step 1
Type Photoshop in the Search box next to the Start button.
Step 2
Click on the Adobe Photoshop CC 2015 option.
The startup screen of the Photoshop appears as shown in Figure 7.1.

We can customise the appearance of the Photoshop window according to our own preferences. In this chapter, we have chosen to display the interface in light grey colour by choosing the Edit ► Preferences ► Interface menu option.
While working in Photoshop, we can choose to create a new image or open an existing image for editing. To open an existing image, choose File ► Open. The Photoshop workspace appears as shown in the following figure.

Components of The Photoshop Workspace
The Photoshop workspace consists of the various components (Fig. 7.2). They are:

Tools Panel: The Tools panel offers various tools that let us select, edit, draw, paint and view images (Fig. 7.3). To use any tool, we can click on its icon in the Tools panel. Most of the tools in the Tools panel show a small triangle at the lower-right corner. Click and hold the mouse on these tools to view more tools of the same category.
Menu Bar: The Menu bar provides menu commands for performing various tasks in Photoshop. The Photoshop menus are arranged by topic. For example, the Layer menu provides options for working with layers.

Options Bar: The Options bar provides options related to the tool currently selected in the Tools panel. For example, to choose the thickness of the Brush Tool selected in the Tools panel, we use the Options bar.

Panels: Photoshop offers various other panels that help us monitor and change various properties of an image.

Document Window: It is the area that displays the image file that we will work on. The name of the image file appears as a tab at the top of the Document window.

Creating a New Photoshop File
We can create a new image by choosing the File ► New menu option. This displays the New dialog box (Fig. 7.4) wherein we can set properties related to the new file.

In the New dialog box, we can change the following properties.

► Name: To specify the name of an image file.

► Width and Height: To specify the size of an image file in different units of measurement such as pixels, inches, centimeters or points.

► Resolution: To specify the number of pixels to be displayed per inch or per cm. Resolution determines the sharpness and clarity of an image. Higher the resolution, better will be the clarity of an image.

► Color Mode: To specify the colour mode such as RGB, CMYK or Grayscale to be used for displaying or printing an image. Colour mode determines the number of colours and the file size of an image.

►Background Contents: To provide information about the background of an image. We can choose from three options—white, background colour and transparent.

Saving a File
We can save the new Photoshop file using the File ► Save or File ► Save As menu option. Photoshop supports various types of file formats such as PSD, TIFF, GIF, JPEG and PDF. The Photoshop file format is .PSD.

Using The Tools Panel

The Tools panel contains a collection of tools that let us work with different aspects of images. Some of the categories of tools that will be discussed in this class are —Selection tools, Painting tools, Drawing tools, Type tools and Retouching tools.
Before we proceed to learn about the different categories of tools, let us first learn about the Color Picker tool in the Tools panel.

The Color Picker tool lets us select a colour for setting the foreground and the background colours. The currently selected foreground colour gets displayed in the upper box and the currently selected background colour is displayed in the lower box.
The foreground colour is used for painting, filling shapes and drawing strokes (lines). The background colour is used to fill the erased areas of an image.
The steps to change the foreground or the background colour using the Color Picker are:
Click the upper box or the lower box of the Color Picker in the Tools panel. The Color Picker dialog box appears (Fig. 7.5).
Select a colour by performing any one of the following tasks.

► Drag the white triangles along the color slider, or
► Click in the Color slider, or
► Click in the Color field.

Click OK.

Selection Tools
The Selection tools allow us to select a portion or subset of an image to work on. This help us in editing and applying effects only to the selected portions of an image while leaving the unselected areas unaffected. The selected portions are highlighted using a dashed border.

In this section, we will learn about the following categories of selection tools—
Marquee Tools, Lasso Tools, Quick Selection Tool, Magic Wand Tool and Crop Tool.
► Rectangular Marquee Tool

The marquee tools include:
allows us to make a selection in a rectangular shape.
► Elliptical Marquee Tool allows us to make a selection in an elliptical or a circular shape.
► Single Row Marquee Tool allows us to make a selection as a row that is one pixel wide.
► Single Column Marquee Tool allows us to make a selection as a column that is one pixel wide.
The steps to be followed to select an area using the Marquee tools are:
Step 1
Open the image.
Step 2
Choose the required Marquee Tool.
Step 3
Drag the mouse over the surface of the image to mark the selection (Fig. 7.7 and Fig. 7.8).

Step 1:
Open the image.
Step 2
Choose the required Lasso Tool and follow the given steps to understand the working of each tool.
► Lasso Tool: The Lasso Tool allows us to make selections by drawing a freehand area. For this, drag the mouse around the portion of the image to be selected (Fig. 7.10).

► Polygonal Lasso Tool: The Polygonal Lasso Tool allows us to make selections by clicking specific points around an image. To use this tool, click anywhere on the image to mark the starting point and then click at the position where you want the first straight segment to end. Continue clicking to mark endpoints for subsequent segments till the area you wish to select is enclosed forming a polygon. To close the selection, position the pointer over the starting point and click (Fig. 7.11).

► Magnetic Lasso Tool: The Magnetic Lasso Tool allows us to select objects by sticking the selection border to the edges of an object. This tool is particularly useful when there is a huge contrast between the foreground objects and the background objects of an image. Magnetic Lasso Tool identifies this contrast and draws points to create a selection area as you drag the mouse around the edges of the object to be selected (Fig. 7.12).

The Magic Wand Tool lets us select those areas of an image which share a similar colour. When using this tool, we can also set various options for specifying the exact selection in the Options bar (Fig. 7.13). These options include:

► Tolerance: Tolerance determines how closely the colours should be matched. Specifying a low value selects colours that are very similar to the pixel where you clicked. Specifying a higher value selects a wide range of colours.
► Anti-aliased: This option lets us define a smooth edge for the selection.
► Contiguous: This option lets us select only adjacent areas that share the same colours.

Drawing Tools
We can use tools such as Rectangle, Rounded Rectangle, Ellipse, Polygon and Line from the Tools panel for drawing various shapes in Photoshop. We can also draw other shapes such as a blob, a heart and arrows using the Custom Shape Tool.

The steps to use the Custom Shape Tool are:
Step 1
Select the Custom Shape Tool from the Tools panel.
Step 2
Select a shape from the Shape pop-up panel in the Options bar
(Fig. 7.21).
Step 3
Click and drag the mouse to draw the selected custom shape
(Fig. 7.22).

Painting Tools
The Painting Tools are used for changing the fill colour of an image. The Painting tools available in Photoshop are Brush Tool, Pencil Tool, Color Replacement Tool, History Brush Tool, Paint Bucket Tool and Gradient Tool.

You can use the Brush Tool and the Pencil Tool to apply colour with brush strokes while the Gradient Tool and the Paint Bucket Tool can be used to apply colour to large areas. Let us discuss some of these tools.

You can set various options in the Options bar (Fig. 7.23). These options include:

► Brush Preset Picker: It lets us change the master diameter of the brush. The master diameter determines the size of the brush. We can change the size either by dragging the master diameter slider or by selecting a preset brush at the bottom of the menu.

► Mode: It allows us to set the painting mode such as to darken and to lighten when applying the brush strokes.

► Opacity: It allows us to set the level of transparency when applying brush strokes. Decreasing the opacity makes your brush more transparent while increasing the opacity makes it less transparent.

► Flow: It allows us to specify how quickly the paint will be applied.

To use the Brush Tool, follow the given steps.
Step 1
Open the image file.
Step 2
Choose an appropriate foreground colour from the Color Picker.

Step 3
Select the Brush Tool.
Step 4
Set the appropriate Brush size, Mode, Opacity and Flow for the Brush from the Options bar.
Step 5
Drag the mouse to paint strokes using the brush on the image (Fig. 7.24).

The Gradient Tool is used to fill selected areas with a blend of multiple colours. You can choose from the Linear, Radial, Angle, Reflected or the Diamond gradient types. The steps to use the Gradient Tool are:
Step 1
Select the area of the image in which you wish to apply the gradient fill using one of the Selection tools.
Step 2
Select the Gradient Tool.
Step 3
Double-click on the Gradient Sample box in the Options bar (Fig. 7.25). The Gradient Editor dialog box appears (Fig. 7.26).

Step 4
Select a Preset gradient fill or create a New gradient fill in the Gradient Editor dialog  box. Click on OK to close the dialog box.

Step 5
Choose an appropriate gradient type in the Options bar.
Step 6
Place the mouse pointer in the selected area where you want to set the starting point of the gradient and drag to define the end point (Fig. 7.27).

The Color Replacement Tool in Photoshop enables you to replace the colour of an image with the colour of the foreground. When you choose this tool, the mouse pointer changes to the target symbol. As you drag the Color Replacement Tool, it picks up a sample of the colour that has to be replaced. That colour is then replaced with the colour that you have selected for the foreground from the Color Picker.
You can also specify various settings to control the behaviour of the Color
Replacement Tool in the Options bar (Fig. 7.28). Two of these settings include:

► Tolerance: Tolerance determines how closely the colours should be matched for sampling. Specifying a lower value selects colours that are very similar to the pixel where you clicked. Specifying a higher value selects a wide range of colours.
► Limits: It allows you to specify whether only the colour of adjacent pixels containing the sample colour should be replaced or the colour of the non-adjacent areas should also be replaced.

The steps to use the Color Replacement Tool are:
Step 1
Set the foreground colour using the Color Picker in the Tools panel.
Step 2
Select the Color Replacement Tool. The pointer shape changes to a target symbol.
Step 3
Set the appropriate options for Tolerance and Limits in the Options bar.
Step 4
Drag the target symbol over the port where you want to change the colour.

CBSE Class 9 Science Practical Skills – Melting Point of Ice and Boiling Point of Water

EXPERIMENT

AIM
To determine the melting point of ice and the boiling point of water.

OBJECTIVE A
To determine the melting point of ice.

MATERIALS REQUIRED
Ice cubes, filter paper, beaker, wire gauze, tripod stand, burner, thermometer, stirrer, clamp stand.

THEORY
Ice is the solid form of H₂0. Its melting point is 0 °C i.e., the forces of interaction between the molecules in the solid form of H₂0 can be broken down at 0 °C and solid H₂0 gets converted into liquid water.

PROCEDURE

1. Take some ice cubes. Dry them using the filter paper and put them quickly in a beaker.
2. Place the beaker on a wire gauze kept over a tripod stand.
3. Suspend a thermometer, into the ice cubes, with the help of a clamp stand.
   
4. Heat the ice cubes and stir continuously for uniform heating.
5. Note the temperature (t₁) when ice starts melting.
6. Heat continuously till ice melts completely. Note this temperature (t₂).
7. Record your observations in the table.

OBSERVATIONS
Observation Table

Mean value of temperatures =  \(\frac { { t }_{ 1 }+{ t }_{ 2 } }{ 2 }\)
Boiling point of water = ……………..°C.

RESULT
The melting point of ice =………… °C.

PRECAUTIONS

1. Ice should be dry before using for melting point determination.
2. The bulb of the thermometer should be dipped in ice and should be surrounded on all sides with ice.
3. Maintain a uniform temperature, by continuous stirring.
4. Temperature should be measured by keeping eyes in line with the level of mercury.

OBJECTIVE B
To determine the boiling point of water.

MATERIALS REQUIRED
Distilled water, boiling tube, rubber cork with two bores, delivery tube, clamp stand, pieces of pumice stone/ porcelain pieces, beaker, thermometer, burner.

THEORY
H₂0 exists in three different physical states-solid ice, liquid water and water vapour. In the liquid state, the forces of interaction are less and therefore, water exists as a liquid at room temperature. The boiling point of water is 100 °C, i.e. the vapour pressure of water becomes equal to atmospheric pressure at 100 °C at sea level.

PROCEDURE

1. Take about 50 ml distilled water in a boiling tube, and add few pieces of pumice stone/porcelain to it.
2. Fix a cork with two bores in the mouth of the boiling tube and fix a thermometer in one bore and delivery tube in the other.
3. Clamp the tube to the stand.
   
4. Place a beaker below the open end of the delivery tube to collect condensed water.
5. Heat the boiling tube by preferably rotating the flame for uniform heating.
6. Note the temperature (t₁) when water starts boiling.
7. Heat continuously till the temperature becomes constant, and water keeps on boiling. Note this temperature (t₂)
8. Record your observations in the table.

OBSERVATIONS
Observation Table

Mean value of temperatures =  \(\frac { { t }_{ 1 }+{ t }_{ 2 } }{ 2 }\)
Boiling point of water = ……………..°C.

RESULT
The boiling poin of water = ……….. °C

PRECAUTIONS

1. Use distilled water only. Impure water and hard water have boiling point greater than 100°C.
2. The bulb of the thermometer should be slightly above the liquid.
3. Add porcelain pieces before heating to avoid bumping.
4. Heat water by rotating the flame.
5. Note the temperature by keeping the eyes in line with the level of mercury.

INTERACTIVE SESSION

Examiner :
Define boiling point of a liquid.
Examinee:
Boiling point of a liquid is the temperature at which the vapour pressure of liquid is equal to the pressure of the gas above it.

Examiner :
What do you understand by vapour pressure of a liquid?
Examinee:
The pressure that the vapours exert on the surface of the liquid at equilibrium is called vapour pressure of that liquid.

Examiner :
What is the difference between evaporation and boiling?
Examinee:

Examiner :
How does the boiling point of water change at high altitudes as compared to at sea level? Why?
Examinee:
The boiling point decreases at higher altitudes because the atmospheric pressure at higher altitudes is less and less energy is required to make vapour pressure equal to atmospheric pressure.

Examiner :
Two liquids A and B have boiling points equal to 35 °C and 70 °C respectively. Which has a higher vapour pressure? Explain why.
Examinee:
Liquid ‘A’ has higher vapour pressure. A liquid which has a higher vapour pressure would require lesser heat energy, so that the vapour pressure becomes equal to atmospheric pressure.

Examiner :
Out of water and ether, which has a higher vapour pressure?
Examinee:
Ether has a higher vapour pressure. The intermolecular interaction between ether molecules is less and therefore it vapourizes easily and has a higher vapour pressure.

Examiner :
On adding a non volatile solute to water, what happens to its boiling point?
Examinee:
The boiling point of water increases.

Examiner :
Why cooking in a pressure cooker is faster?
Examinee:
In a pressure cooker, the pressure is high and therefore, boiling point of water increases and cooking is faster.

Examiner :
What is the melting point of pure ice?
Examinee:
It is 0 °C or 273 K.

Examiner :
How does addition of a non volatile solute effect the melting point of ice?
Examinee:
The melting point of ice decreases.

Examiner :
Can you change a liquid into vapours below its boiling point?
Examinee:
Yes, through the process of evaporation which is a surface phenomenon. For example, drying of clothes at a lower temperature.

Examiner :
Which out of ionic and covalent solids have a lower melting point?
Examinee:
The covalent solid has a lower melting point.

Examiner :
Why do they have a lower melting point?
Examinee:
It is so because covalent compounds have low intermolecular forces of interaction, which can be broken down easily.

Examiner :
Why do ionic compounds have higher melting points?
Examinee:
Ionic compounds have high melting points due to electrostatic forces of interaction existing between the ions.

Examiner :
Non polar compounds are volatile. Give reason.
Examinee:
Non polar compounds have weak van der Waals’ forces existing between the molecules, and they are therefore, volatile.

Examiner :
Why are ionic compounds crystalline?
Examinee:
Ionic compounds are crystalline in nature as they have ions arranged in a specific three dimensional nature.

Examiner :
Using melting points, how can we characterise a substance?
Examinee:
For a pure substance, the melting point will be sharp, i.e. the compound melts completely within a range of 2 °C.

Examiner :
Would the boiling point of distilled water and hard water be the same?
Examinee:
No, becasue hard water contains non volatile impurities (Ca and Mg salts) and therefore hard water will have a higher boiling point.

Examiner :
For clearing snow, CaCl₂ is used. Why?
Examinee:
CaCl₂ lowers the melting point of snow and therefore, snow melts at a lower temperature as compared to its melting point and can therefore, be cleared off.

NCERT LAB MANUAL QUESTIONS

Question 1:
Why is the bulb of thermometer kept above the surface of water while determining the boiling point of water?
Answer:
While determining the boiling point of water the bulb of the thermometer is kept above the surface of water, as steam contains only water vapour and the effect of any non-volatile impurity, if present in water, will be otherwise nullified.

Question 2:
Why does the temperature remain unchanged until the entire solid changes into liquid even if we are heating the solid?
Answer:
The temperature remains unchanged until the entire solid changes into liquid even on further heating as the heat provided is used to overcome the forces of attraction present between the particles of a solid and to change the state from solid to liquid.

Question 3:
Why do we fix a two holed-cork in the round bottom flask while determining the boiling point of water?
Answer:
A two holed-cork is fixed in the round bottom flask while determining the boiling point of water

1. to allow the water vapour to escape from the flask, otherwise the pressure inside the flask becomes high and may lead to bursting of the round bottom flask and
2. to fix the thermometer and read the temperature when water boils.

PRACTICAL BASED QUESTIONS
Multiple Choice Questions/VSA

Question 1:
In the experiment, “Determination of melting point of ice”, the reading of the thermometer must be noted when
(a) temperature starts rising
(b) temperature becomes constant
(c) ice starts melting
(d) whole of the ice gets melted.

Question 2:
When we observe the melting of ice, the melting point of ice is a constant temperature at which
(a) both ice and water are present
(b) only water is present
(c) only ice is present
(d) first ice and then only water.

Question 3:
Two students Arpit and Rakshita are asked to arrange the apparatus to determine the boiling point of water. They arranged the apparatus as shown below by figures A and B respectively.

The diagram in which the apparatus is correctly arranged is
(a) A only
(b) B only
(c) both A and B
(d) neither A nor B.

Question 4:
Reema, Archna, Shakti and Ilia made the arrangement I, II, III, IV for determination of boiling point of water. Which one of them has made the correct set up?

(a) I
(b) II
(c) III
(d) IV

Question 5:
When a thermometer is kept in the ice the reading shows that
(а) temperature keeps increasing
(b) temperature keeps decreasing
(c) temperature increases first and then decreases
(d) temperature first decreases and then remains constant at 0 °C.

Question 6:
A student set-up an apparatus for finding the melting point of ice. When half of the ice melted, the temperature shown by thermometer is
(a) more than 0 °C
(b) less than 0 °C
(c) zero degree Celsius
(d) none of the above.

Question 7:
A thermometer has 20 equal divisions between 90 °C and 100 °C marks. A student while determining the boiling point of water finds that the mercury thread becomes stationary at the 19th mark above 90 °C. He should record the boiling point of water as
(a) 90.19 °C
(b) 99.5 °C
(c) 109 °C
(d) 119 °C

Question 8:
A student takes some water in a beaker and heats it over the flame for determining its boiling point. He keeps on taking its temperature readings. He would observe that the temperature of water
(a) keeps on increasing regularly
(b) keeps on increasing, irregularly
(c) first increases slowly, then decreases rapidly and eventually becomes constant
(d) first increases gradually and then becomes constant.

Question 9:
In the determination of boiling point of water, correct reading in the thermometer is noted when
(a) water starts boiling.
(b) whole of the water evaporates.
(c) temperature starts rising.
(d) temperature becomes constant.

Question 10:
At 0 °C or 273 K, the physical state of water is observed as
(a) solid
(b) liquid
(c) vapour
(d) both solid and liquid.

Question 11:
In the determination of boiling points of water, it is advised to put the bulb of the thermometer above the water rather than in water, it is to
(a) reduce the error due to atmospheric pressure
(b) make sure that boiling point obtained is accurate even when water sample contains non-volatile impurities dissolved
(c) reduce the error due to expansions of glass because of heat
(d) obtain the, boiling point accurately even in a shorter time

Question 12:
For the accurate determination of the boiling point of water, we use
(a) tap water
(b) distilled water
(c) boiled water
(d) hard water (solution).

Question 13:
Two compounds A and B have boiling points as 40 °C and 170 °C. The nature of the compounds are respectively
(a) ionic, covalent
(b) ionic, ionic
(c) covalent, ionic
(d) covalent, covalent.

Question 14:
The inferences drawn by the temperature versus time graph are

(а) during melting, temperature of substance does not change
(b) temperature rises after all amount of ice melts
(c) at a specific temperature water starts boiling and temperature remains the same during the conversion of water into steam
(d) all of these.

ANSWER KEY
Multiple Choice Questions/VSA

1. (b)
2. (a)
3. (b)
4. (c)
5. (d)
6. (c)
7. (6)
8. (d)
9. (d)
10. (d)
11. (b)
12. (b)
13. (c)
14. (d)

Science Practical SkillsScience LabsMath Lab ManualMath Labs with ActivityMath Labs

CBSE Notes for Class 8 Computer in Action – Images and Lists in HTML

In the previous class, you learnt about the basic formatting tags used for designing a webpage in HTML. Some of these tags include <BODY>, <P>, <FONT>, <HR> and heading tags. The description and the attributes related to these tags are outlined in Table 4.1

In this chapter, we will learn how to insert images and lists in a webpage to enhance the look and feel of a webpage.

INSERTING IMAGES (<IMG>TAG)
Images enhance the overall appearance of a webpage. Images make the websites look interesting. While designing the webpages, you should maintain a balance between the use of text and images. However, excessive use of images may slow down the download of a webpage. The image file formats that are supported by most web browsers include GIF, JPEG and PNG.
In HTML, the images are inserted using the <IMG> tag. It is an empty tag. Table 4.2 lists the attributes of the <IMG> tag.

The following HTML code uses different attributes of the <IMG> tag to display the output as shown in Figure 4.2.

The output of the above code is as follows.

Using tke Align Attribute of < IMG> Tag
The align attribute of the <IMG> tag let us specify the placement of image on a webpage. To align an image with respect to the margins, we use left or right as the attribute value as shown in the following HTML code.

The output of the above code is as follows.

The other three values that can be assigned to the align attribute are—top, middle and bottom. These values align an image with respect to the text on a webpage. The following HTML code uses these attribute values and displays the output as shown in Figure 4.6.

The output of the above code is as follows.

CREATING LISTS
Lists are a great way of organising a lot of information in webpages. The two most commonly used lists are:

• Ordered list
• Unordered list

Let us learn about these types of lists.

Ordered List (<OL> Tag)
Ordered lists, also called numbered lists, are used when the list items have a specific numerical order or ranking. An ordered list is enclosed within the <OL> and the </OL> tags. Each item in the list is marked using the <LI> (List Item) tag. The default numbering style is 1, 2, 3… and so on.
Table 4.3 lists some of the important attributes of the <OL> tag.

The following HTML code uses different attributes of the <OL> tag and displays the output as shown in Figure 4.8.

Table 4.4 shows some examples of type and start attributes of the <0L> tag.

Unordered Lists (<UL> Tag)
Unordered lists are also known as bulleted lists. In unordered lists, the list items do not have a specific order. An unordered list is enclosed within the <UL> and </UL> tags. Each item in the list is marked using the <LI> (List Item) tag.
Table 4.5 lists the attribute of the <UL> tag.

The following HTML code uses the type attribute of the <UL> tag and displays the output as shown in Figure 4,10.

Table 4.6 outlines the output displayed when you use different values for the type attribute of the <UL> tag.

NESTED LISTS
Ordered and unordered lists can be nested within each other to form multilevel lists. The following HTML code displays the output as shown in Figure 4.12.

CBSE Previous Year Solved  Papers  Class 12 Chemistry Delhi 2013

Time allowed: 3 hours                                                                                      Maximum Marks: 70

General Instructions:

1. All questions are compulsory.
2. Questions number 1 to 5 are very short-answer questions and carry 1 mark each.
3. Questions number 6 to 10 are short-answer questions and carry 2 marks each.
4. Questions number 11 to 22 are also short-answer questions and carry 3 marks each.
5. Questions number 23 is a value based question and carry 4 marks.
6. Questions number 24 to 26 are long-answer questions and carry 5 marks each.
7. Use log tables, if necessary. Use of calculators is not allowed.

SET I

Note: Except for the following questions, all the remaining questions have been asked in previous sets.

Question.1. How many atoms constitute one unit cell of a face-centered cubic crystal ?
Answer : 4 atoms constitute one unit cell of a face centered cubic crystal. It can be determined from the number of atoms contributed from the faces and the corners of the unit cell as:
(8 corners x 1/8 atom per corner = 1 atom) + (6 faces x 1/2 atom per unit face = 3 atoms)
Total number of atoms per unit cell =1+3 = 4 atoms.

Question.2. Name the method used for refining of Nickel metal.
Answer: Method used for refining of nickel metal is Mond’s process.

Question.3. What is the covalency of nitrogen in N₂0₅?
Answer: In N₂0₅, the covalency of N is restricted to ‘4’ due to sp² hybridisation of nitrogen atom involving one 2s and three 2p orbitals.

Question.4.

Question.5. What happens when CH₃-Br is treated with KCN?
Answer:

It is a nucleophilic substitution reaction.

Question.6. Write the structure of 3-methyl butanal.
Answer:

Question.7. Arrange the following in increasing order of their basic strength in aqueous solution: CH₃NH₂, (CH₃)₃N, (CH₃)₂ NH.
Answer:

Question.8. What are the types of RNA molecule which perform different functions?
Answer: Three types of RNA molecules which perform different functions are :
(i) Messenger RNA (m-RNA)
(ii) Transfer RNA (t-RNA)
(iii) Ribosomal RNA (r-RNA)

Question.9. 18 g of glucose, C₆H₁₂O₆ (Molar Mass = 180g/mol) is dissolved in 1 kg of water in a sauce pan. At what temperature will this solution boil?
(K_b for water = 0.52 K kg mol^-1, boiling point of pure water = 373.15 K)

Question.10. The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm^-1. Calculate its molar conductivity.

Question.11. Write the dispersed! phase and dispersion medium of the following colloidal system ?
(i) Smoke (ii) Milk.
OR
What are lyophilic and lyophobic colloids? Which of these , sols can be easily coagulated on addition of small amounts of electrolytes?
Answer: (i) Dispersed phase in smoke : Solid, dispersion medium in smoke : Gas
(ii) Dispersed phase in milk : Fats (liquid), dispersion medium in milk: Water (liquid)
OR
Answer : Lyophilic colloids (Liquid Loving) : These are the colloidal solutions in which dispersed phase has great affinity for dispersion medium. Such solutions are quite stable and are reversible in nature. E.g. starch, proteins, etc.
Lyophobic Colloids (Liquid Hating): These are the colloidal solutions in which dispersed phase has very little affinity for the dispersion medium. Such solutions are unstable and are irreversible in nature. Eg. (As₂S₃ Sol).
Lyophobic colloids can be easily coagulated because on addition of small amount of electrolyte, the charge on colloidal particles is removed, as a result the particles will come closer to each other and then aggregate to form a cluster which settle down under the force of gravity.

Question.12. Write the differences between physisorption and chemisorption with respect to the following:
(i) Specificity (ii) Temperature dependence
(iii) Reversibility and (iv) Enthalpy change
Answer:

Question.13. (a) Which solution is used for the leaching of silver metal in the presence of air in the metallurgy of silver?
(b) Out of ‘C’ and ‘CO’, which is a better reducing agent . at the lower temperature range in the blast furnace to extract iron from the oxide ore?

Question.14. What happens when
(i) PCl₅ is heated? (ii) H₃P0₃ is heated?
Write the reaction involved.

Question.15. (a) Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
(b) Which of the following cations are coloured in aqueous solutions and why?
Sc³⁺, V³⁺, Ti⁴⁺, Mn²⁺ (Atomic Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
Answer: (a) Cu is the only metal in the first transition series (3d series) which exhibits +1 oxidation state more frequently. This is because the electronic configuration of Cu is 3d¹⁰ 4s¹ and after losing one s electron it acquires a stable 3d¹⁰ configuration.
(b) The colour of cations depend upon the number of unpaired electrons present in d-orbital. The electronic configuration of the following cations is as follows :
Sc (Atomic number 21) = Sd¹s² and Sc³⁺ = 3d°4s°. As d-orbital is empty, it is colourless.
V (atomic number 23) = 3d³4s² and V³⁺ = 3d²4s°. As d-orbital is having 2 unpaired electrons, it undergoes d-d transition and depicts green colour.
Ti (Atomic number 22) = 3d²4s² and Ti⁺⁴ = 3d°4s°. As ‘d’ orbital is empty, it is colourless.
Mn(Atomic number 25) = 3d⁵4s² and Mn⁺²=3d⁵4s°. As ‘d’ orbital has 5 unpaired electrons, it depicts pink colour.
Thus, V³⁺ and Mn²⁺ ions are coloured in their aqueous solution due to presence of unpaired electron.

Question.16. Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same.
Answer: Chlorobenzene is extremely less reactive towards a’ nucleophilic substitution reaction because of the following reasons:
1. Resonance effect: The electron pair on chlorine atom is in conjugation with the benzene-electrons of the’ benzene ring which results in the following resonating structures :


This’results in delocalization of electrons of C-Cl bond and a partial double bond character develops in the bond, which makes it difficult for the nucleophile to cleave the C-Cl bond.
2. The nucleophile suffers repulsion from the increased electron density on the benzene ring as a result the nucleophile is unable to make a close approach for the attack on the molecule.

Question.17. Explain the mechanism of the following reaction:

Answer: The mechanism of the reaction is given below:

Question.18. How will you convert:
(i) Propene to Propan-2-ol ?
(ii) Phenol to 2, 4, 6 – trinitrophenol?
Answer: When H₂S0₄ is added to propene, propan-2-ol is formed. The addition of H₂S0₄ takes place in accordance with Markovnikov’s rule.

(ii) When concentrated nitric acid is added to phenol in the presence of sulphuric acid it gives 2, 4,6 – trinitrophenol.

Question.19. (a) What type of semiconductor is obtained when silicon is doped with boron?
(b) What type of magnetism is shown in the following alignment of magnetic moments?

(c) What type of point defect is produced when AgCl is doped with CdCl₂?
Answer: (a) When silicon is doped with boron, p-type semiconductor is obtained.
(b) Ferromagnetism is shown in this alignment of magnetic moments.
(c) Impurity defect of ionic solids is produced when AgCl is doped with CdCl₂.

Question.20. Determine the osmotic pressure of a solution prepared by dissolving 2.5 x 10^-2g of K₂S0₄ in 2L of water at 25°C, assuming that it is completely dissociated.
(R = 0.0821 L atm K^-1 mol^-1, Molar mass of K₂S0₄ = 174 g mol^-1)

Question.21. Calculate the emf of the following cell at 298 K:

Question.22. How would you account for the following?
(i) Transition metals exhibit variable oxidation states.
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
(iii) Transition metals and their compounds act as catalyst.
OR
Complete the following chemical equations:
(i) Cr2O₇^2- + 6Fe²⁺ + 14H⁺ —>
(ii) 2CrO₄^2- + 2H⁺ —>
(iii) 2MnO₄^–  + 5C2O₄^2-  + 16H⁺ —>
Answer: (i) The variable oxidation states of transition elements is due to the participation of ns and (n-1)d-electrons in bonding. Lower oxidation state is exhibited when ns- electrons take part in bonding. Higher oxidation states are exhibited when (n-1) d-electrons take part in bonding.
(ii) This is because atomic radii of 4d and 5d transition elements are nearly same. This similarity in size is a consequence of lanthanide contraction which is due to weak shielding of d-electrons. As a result, the radii of Hf becomes nearly equal to that of Zr.
(iii) The catalytic activity of transition elements and their compound is due to the following reasons:
(i) Due to their tendency to shown variable oxidation state transition metal form instable intermediate compounds and provideds a new path for the reaction with lower activation energy.
(ii) In some cases, the transition metals provide a suitable large surface area with free valencies ion which reactant are adsorbed.
OR

Question.23. Write the IUPAC names of the following coordination compounds:
(i) [Cr(NH₃)₃Cl₃]
(ii) K₃[Fe(CN)₆]
(iii) [CoBr₂(en)₂]⁺, (en = ehylenediamine)
Answer: (i) Triammine trichloridochromium(III)
(ii) Potassium hexacyanoferrate(III)
(iii) Dibromidobis-(ethylene-diammine) cobalt (III) ion .

Question.24. Give the structures of A, B and C in the following reactions:

Question.25. Write the names and structures of the monomers of the following polymers:
(i) Buna – S (ii) Neoprene (iii) Nylon-6, 6

Question.26. After watching a programme on TV about the adverse effects of junk food and soft drinks on the health of school children, Sonali, a student of Class XII, discussed the issue with the principal. Principal immediately instructed the canteen contractor to replace the fast food with the fibre and vitamins rich food like sprouts, salad, fruits etc. This decision was welcomed by the parents and the students.
After reading the above passage, answer the following questions:
(a) What values are expressed by Sonali and the Principal of the school?
(b) Give two examples of water-soluble vitamins.
Answer : (a) The values showed by Sonali are awareness regarding adverse effect of junk food and concern for the health of her school mates. The value showed by the Principal is responsible behaviour in listening to Sonali’s views and taking prompt action in replacing junk food with healthy food.
(b) The two water soluble vitamins are vitamin B2 (Riboflavin) and Vitamin C (Ascorbic acid).

Question.27. (a) Which one of the following is a food preservative? Equanil, Morphine, Sodium benzoate
(b) Why is bithional added to soap?
(c) Which class of drugs is used in sleeping pills?
Answer : (a) Sodium benzoate is used as a food preservative whereas equanil is a tranquilizer and morphine is a narcotic analgesic.
(b) Bithional is an antiseptic so it is added to soaps to reduce
the odours produced by bacterial decomposition of organic matter on the skin.
(c) Tranquilizers relieve stress, fatigue by inducing sense of well being, so they are used in sleeping pills.

Question.28. (a) A reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
(b) A first order reaction takes 40 minutes for 30% decomposition. Calculate t_1/2 for this reaction. (Given: log 1.428 = 0.1548)
OR
(a) For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
(b) Rate constant ‘If of a reaction varies with temperature ‘T’ according to the equation:

(ii) On increasing the concentration of‘A’ three times i.e. 3A; the rate of reaction becomes 9 times of the initial rate.
Rate = K[3A]² [B]=9K[A]² [B] = 9 times rate.
(iii) On increasing the concentration of A and B as 2A and 2B. The rate of reaction becomes 8 times of the initial rate. Rate = K[2A]²[2B] = 8K[A]²[B] = 8 times rate

Question.29. (a) Give reasons for the following:
(i) Bond enthalpy of F₂ is lower than that of Cl₂.
(ii) PH₃ has lower boiling point than NH₃.
(b) Draw the structures of the following molecules:
(i) BrF₃ (ii) (HP0₃)₃ (iii)XeF₄ OR
(a) Account for the following:
(i) Helium is used in diving apparatus.
(ii) Flourine does not exhibit positive oxidation state.
(iii) Oxygen shows catenation behaviour less than sulphur.
(b) Draw the structures of the following molecules.
(i) XeF₂ (ii) H₂S₂OS
Answer: (a) (i) Bond enthalpy of F₂ is lower than that of Cl₂ because ‘F’ atom is small in size and due to this the electron- electron repulsions between the lone pairs of F-F electrons are very large. Thus, the bond dissociation energy of F2 is lower than that of Cl₂.
(ii) PH₃ has lower boiling point than NH₃ because NH₃ molecule possess intermolecular hydrogen bondings which binds them strongly, whereas, PH₃ has weaker van der Waals forces. Thus PH, has a lower boiling point than NH₃.
(b) (i) BrF₃, Bent T-shape

OR
(a) (i) Helium mixed with oxygen under pressure is given to sea- divers for artificial respiration because of its very low solubility in blood. Air is not given because nitrogen present in air being soluble in blood will give a painful sensation called bends by bubbling out blood on moving from high pressure to the atmospheric pressure. Thus, oxygen-helium mixture is used.
(ii) Fluorine being the most electronegative atom does not exhibit positive oxidation state because, it does not have d-orbitals for octet expansion and therefore, it shows only a negative oxidation state of -1.
(iii) Oxygen shows catenation behaviour less than sulphur because the oxygen atom is smaller in size as compared to -> sulphur due to this the lone pair of electrons in 0-0 bonds in oxygen experiences more repulsions as compared to the S-S bonds and thus, S-S forms strong bond.

Question.30. (a) Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger acid than phenol. Give two reasons.
(b) How will you bring about the following conversions?
(i) Propanone to propane
(ii) Benzoyl chloride to benzaldehyde
(iii) Ethanal to but-2-enal.
OR
(a) Complete the following reactions :

(b) Give simple chemical tests to distinguish between the . following pairs of compounds :
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol.
Answer : (a) On losing a proton, carboxylic acids forms carboxylate ion and phenol forms phenoxide ion as follows :

The conjugate base of carboxylic acid has two resonance structures in which negative charge is declocalized over two oxygen atoms which stabilizes the carboxylate ion. On the other hand, in phenoxide ion the charge is delocalized over entire molecule on the less electronegative atom, thus resonance of phenoxides is not important in comparison to resonance in carboxylate ion.
Further, in carboxylate ion the negative charge is effectively delocalized over two oxygen atoms whereas it is less effectively delocalized over one oxygen atom and less electronegative carbon atom.
Thus, phenol is less acidic than carboxylic acids. In other words, carboxylic acids are stronger acids than phenol.


(b) (i) Ethanol and Propanal:
Iodoform Test : When ethanol is treated with sodium liydroxide and ammonia, iodoform is obtained.

SET II

Note: Except for the following questions, all the remaining questions have been asked in previous sets.

Question.1. What type of stoichiometric defect is shown by AgCl?
Answer: Frenkel defect is shown by AgCl.

Question.2.

Question.4. What type of bonding helps in stabilizing the a-helix structure of proteins?
Answer: Hydrogen bonding between the -NH group of each amino acid residue and the > C = O of an adjacent turn of the helix helps in stabilizing the <-helix- structure of proteins.

Question.6. What inspired N. Bartlett for carrying out reaction between Xe and PtF₆?
Answer: N. Bartlett observed that the first ionization enthalpy of molecular oxygen is almost identical with that of xenon. So after preparing red coloured compound 02+PtF6- he made efforts to prepare Xe+PtF₆– by mixing PtF₆ and Xe.

Question.7. What happens when ethyl chloride is treated with aqueous KOH?
Answer: When C₂H₅Cl reacts with aq. KOH, substitution Nucleophilic bimolecular (S_N2) reaction takes place and Ethanol is formed.

Question.8. Write the structure of 4-chloropentan-2-one.

Question.9. How will you convert the following?
(i) Propan-2-ol to propanone.
(ii) Phenol to 2,4,6 – tribromophenol?
Answer: (i) Propan-2-ol to propanone :

Question.11. What is the difference between oil/water (O/W) type and water/oil (W/O) type emulsions? Give an example of each type.
Answer: Emulsion of oil-in-water has oil has dispersed phase and water as dispersion medium. For example, Milk etc. Emulsion of water-in-oil has water as dispersed phase and oil as dispersion medium. For example, Cod liver oil etc.

Question.17. (a) Which of the following ores can be concentrated by froth floatation method and why?
Fe₂0₃, ZnS, Al₂0₃
(b) What is the role of silica in the metallurgy of Copper?
Answer: (a) Only sulphide ores are concentrated by this process because pine oil selectively wets the sulphide ore and hence bring it to the froth.
(b) Silica is added in the reverberatory furnance during the extraction of copper to remove iron oxide present in the ore. * Iron oxide reacts with silica and is removed as slag of iron silicate.

Question.18. (a)Why does p-dichlorobenzene have a higher m p than its o- and m- isomers? (b) Why is (—) — Butan-2-ol is optically inactive?
Answer: (a) p-dichlorobenzene have higher- melting point than ortho and meta isomer. This is because the para isomer is having a symmetrical structure and therefore, its packing is more efficient as compared to the ortho and meta isomer, therefore, it shows higher melting point.

(b) The (+) – Butan-2-ol is optically inactive because it is racemic mixture and exists in two enantiomeric forms which are non-superimposable mirror images of each other. Both the isomers are present in equal amounts therefore, it does not rotate the plane of polarized light and is optically inactive.

Question.23. Write the names and structures of the monomers of the following polymers:
(i) Polystyrene
(ii) Dacron
(iii) Teflon
Answer: Polymers with their monomers and their structures:

Question.27. Write the types of isomerism exhibited by the following complexes:

SET III

Note: Except for the following questions, all the remaining questions have been asked in previous sets.

Question.1. What type of substances would make better Permanent Magnets, Ferromagnetic or Ferrimagnetic?
Answer: Ferromagnetic substance would make better permanent magnets because when the ferromagnetic substance is placed in a magnetic field, all domains get oriented in the direction of magnetic field and strong a magnetic effect is produced.

Question.3. What is the composition of ‘Copper matte’?
Answer: Composition of‘Copper matte’ is Cu₂S and FeS.

Question.5. What is a glycosidic linkage?
Answer: The linkage between the two monosaccharide units through oxygen atom accompanied by the loss of a water molecule is called glycosidic linkage.

Question.6. Write the IUPAC name of (CH₃)₂CH.CH(Cl)CH₃
Answer:

Question.7. Which compound in the following pair undergoes faster S_N1 reaction?

Question.8. Write the structure of p-Methylbenzaldehyde molecule.
Answer:

Question.9. What is the difference between multi-molecular and macromolecular colloids? Give one example”of each.
Answer: Difference between Multi-molecular and Macromolecular colloids:

Question.14. (a) Give an example of zone refining of metals.
(b) What is the role of cryolite in the metallurgy of aluminum?
Answer: (a) Zone Refining of metals : This method is used for production of semiconductor and other metals of very high purity like germanium, silicon, boron, gallium and indium.
(b) Role of cryolite in metallurgy of Aluminium : Cryolite is added to.lower the melting point of mixture and to increase the conductivity of electrolyte.

Question.17. Account for the following:
(i) The C-Cl bond length in chlorobenzene is shorter than that in CH₃-Cl.
(ii) Chloroform is stored in closed dark brown bottles.
Answer: (i) This is due to partial double bond character to C-Cl bond (due to resonance in C₆H₅Cl).
(ii) Chloroform in the presence of air gets oxidized to phosgene. Phosgene is carbonyl chloride and is represented as COCl₂. To prevent the formation of phosgene, chloroform is stored in dark coloured bottles. The reaction represented as CHCl₃ + 1/2 O₂ –> COCl₂ + HCl

Question.18. How will you convert:
(i) Propene to Propan- 1-ol? (ii) Ethanal to Propan-2-ol?
Answer:

Question.23. Give the structures of products A, B and C in the following reactions:

Question.27. Write the names and structures of the monomers of the following polymers:
(i) Bakelite (ii) Nylon-6 (iii) Polythene

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