Nirmala

Deep Water Important Questions CBSE Class 12 English

Short Answer Type Questions (3 Marks, 30-40 words)

Question.1. Which two incidents in Douglas’ early life made him scared of water? (Compartment 2014)
Answer. When Douglas was three or four years old, his father took him to a beach in California. There he was knocked down by strong waves, was almost buried under water, and got breathless. Though he hung on to his father, he was quite frightened. Secondly, when Douglas was ten or eleven, a big bully of a boy tossed him into the deep end of the YMCA pool. He could not come to the surface, in spite of all his efforts, and became panicky. These two incidents made Douglas scared of water.

Question.2.Why did Douglas prefer to go to YMCA swimming pool to learn swimming?
(Compartment 2014)
or
Which factors made Douglas to decide in favour of YMCA pool? (All India 2011)
Answer. According to Douglas, the YMCA pool was safer compared to the Yakima River. The river was quite deep and there were several cases of drowning reported about it. As against the uncertain depth of the river, the pool was only two or three feet deep at the shallow end. Though its depth was about nine feet at the deeper end, yet the drop was gradual, and Douglas could rely on it.

Question.3.What did Douglas feel and do when he was pushed into the swimming pool?
(Compartment 2014)
or
What were the series of emotions and fears that Douglas experienced when he was thrown into the pool? (Foreign 2011)
Answer. When Douglas was thrown into the pool, he did not lose heart and planned to push himself up with all his force. He thought that once he came to the surface, he would paddle to the edge of the pool. Thrice, he tried to come to the surface, but unfortunately his strategy did not work and terror gripped him. His lungs were ready to burst; he was breathless and instead of air, sucked water.

Question.4.How did his swimming instructor ‘build a swimmer’ out of Douglas? (Compartment 2014)
or
How did the instructor turn Douglas into a swimmer? (Delhi 2013)
Answer. The instructor adopted a systematic method to turn Douglas into a swimmer. He first made Douglas shed his initial fear of water by making him cross a pool suspended by a rope attached to a pulley. The instructor held the other end of the rope and relaxed and tightened it from time to time. Then he taught the narrator to breathe while swimming, and finally the leg movements and other strokes.

Question.5. How did Douglas make sure that he conquered the old terror? (All India 2013)
Answer. After the instructor had trained Douglas in the art of swimming, Douglas was still not sure of himself. He felt tiny vestiges of the fear now and then. So, he went to Lake Wentworth and swam. Once when terror returned, he challenged it and did not let it overcome him. Finally, Douglas went to the Warm Lake. There he swam and the fear didn’t return to haunt him again.

Question.6. What efforts did Douglas make to get over his fear of water? (Delhi 2012)
Answer. After several individual attempts to overcome his fear, Douglas finally engaged an instructor. The instructor built a swimmer out of him. But Douglas was not sure. To confirm that the terror would not strike him when he was swimming alone, Douglas decided to go to Lake Wentworth in New Hampshire. At last, he made his terror fly away by swimming across the Warm Lake.

Question.7. Why was Douglas determined to get over his fear of water? (DeM20ii, 2009)
Answer. The misadventure of having a near-drowning experience left a deep mark on Douglas’ mind.
The phobia of water hampered all his joys of enjoying different water sports like fishing,
canoeing, boating and swimming. He did not want to live with this handicap and so was determined to overcome his fear of water.

Question.8. What did Douglas experience when he went down to the bottom of the pool for the
first time? (Delhi 2011,2010)
Answer. When the author was going down to the bottom of the pool for the first time, those nine feet felt almost like ninety feet. His lungs were ready to burst, but somehow he summoned all his strength and sprang upwards, hoping to reach the surface, but he didn’t pop up to the surface like a cork, as he had imagined. When he opened his eyes he saw nothing but water, his hands too grabbed only water.

Question.9. Why did Douglas go to Lake Wentworth in New Hampshire? (Delhi 2011)
Answer. Douglas was not satisfied with his practice so he decided to go to Lake Wentworth. There when he was swimming in themiddle of the lake, only once did the terror return, but he finally overcame it, and it made him feel better.

Question.10.When Douglas realised that he was sinking, how did he plan to save himself?
(Delhi 2010)
Answer. When a big boy threw Douglas into the water, he went straight down. He was completely frightened. Still, he did not lose his wits and thought of a strategy to make a big jump when his feet touched the bottom, so that he could reach the surface. He even thought that he would lie flat on the surface and finally paddle to the edge of the pool.

Question.11. What sort of terror seized Douglas as he went down the water with a yellow glow?
How could he feel that he was still alive ? (Delhi 2010)
Answer. When Douglas found himself deep down into the water with a yellow glow, stark terror gripped him. The terror ripped him apart and he had no control over it. He felt paralysed, stiff and rigid with fear. Even the screams in his throat were frozen. It was only his throbbing heart that made him realise that he was still alive.

Long Answer Type Questions (6 Marks, 120-150 words)

Question.1. “I crossed to oblivion, and the curtain of life fell.” What was the incident which nearly killed Douglas and developed in him a strong aversion to water? (Foreign 2014)
Answer. The incident which nearly killed Douglas occurred when he was ten or eleven years old. He had decided to learn swimming at the YMCA pool, and thus get rid of his fear of water. One . morning, when he was alone at the pool, waiting for others, a big bully of a boy tossed him into the deep end of the pool. Though he had planned a strategy to save himself as he went down, his plan did not work. He went down to the bottom and became panicky. Thrice he struggled hard to come to the surface, but failed each time. He was almost drowned in the pool. He lost his consciousness and felt that he would die. Though he was ultimately saved, this misadventure developed in him a strong aversion to water.

Question.2. Douglas fully realised the truth of Roosevelt’s statement, “All we have to fear is fear
itself.” How did this realisation help him brush aside his fear and become an expert swimmer? (Foreign 2014)
Answer. Douglas had experienced both the sensation of dying and the terror that the fear of death can cause. Strong will, hard determination, courage and toil as well as honest labour won over all his terrors and fears. The will to live brushed aside all his fears.
In reality all our fears are only psychological, and can be easily won over, if we can control our mind. This realisation makes Douglas resolve to learn swimming by engaging an instructor. This instructor, piece by piece, built Douglas into a swimmer. However, his first step was to drive away Douglas’ fear of water, before training him in swimming techniques. When Douglas tried and swam the length of the pool up and down, small traces of his old terror of water would return. So, he went to Lake Wentworth, dived at Triggs Island and swam two miles across the lake to Stamp Act Island. Finally, he was certain that he had conquered his fear of water.

Question.3. Desire, determination and diligence lead to success. Explain the value of these
qualities in the light of Douglas’ experience in ‘Deep Water.’ (Compartment2014)
Answer. The terror of water followed Douglas wherever he went. To get rid of it, he made a strong determination. He decided to overcome his fear through his “will.” He engaged an instructor who would perfect him in swimming. The instructor first helped him drive away his fear, and then gave him many exercises besides teaching him to exhale and inhale in water.
The practice went on for months together, during which his fear came back to haunt him, but his desire and firm will made him persist in his- efforts. It was only through sheer determination and diligence that Douglas could not only counter his terror, but also become an expert swimmer.
He swam across and back lakes to ensure that his fear of water did not return. He had now completely lost his fear. His desire, determination and diligence succeeded in banishing his fear of water.

Question.4. How did Douglas develop an aversion to water? (Ddhi20i2)
or
“…….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? (All India 2010)
Answer. Douglas developed an aversion to water in his early childhood, When he was three or four
years old, his father took him to a beach in California. The waves knocked him down and
swept over him. He was buried in water. He was frightened but his father was laughing. Perhaps this was the moment his fear of water took root inside his mind.
Further, when Douglas was ten or eleven years old, he decided to learn to swim and went to
the YMCA pool. Here an incident took place that finally established his aversion to water as a big fear. One day when Douglas was alone at the pool sitting on the edge and waiting for others to come, a big boy of 18 years of age threw him into the deep end of the pool.
What followed was a nightmarish experience for him. Douglas tried very, hard and applied all his knowledge to come to the surface of the water but to no avail. Somehow, he was saved. Thus after this fearful incident, his fear of water got implanted in his heart and mind
permanently.

Question.5. How did the instructor make Douglas a good swimmer? (All India 2012)
Answer. To overcome his fear of water, Douglas finally decided to get an instructor to learn
swimming. The instructor started working with him five days a week, an hour each day. The
instructor put a belt around Douglas. A rope was attached to the belt that went through a pulley that ran on an overhead cable. The instructor held on to the end of the rope and , along with Douglas went back and forth, across the pool, hour after hour, day after day,
week after week. On each trip across the pool a bit of panic seized Douglas. It took almost three months before the tension reduced.
Then the instructor taught him to put his face under the water and exhale and to raise his nose and inhale. For weeks, his instructor made him kick with his legs. Until, he was able to command his legs at his will.
In this way, piece by piece, his instructor made Douglas a swimmer. When Douglas perfected each piece, his instructor put them together into an integrated one. As a result, in nearly six months Douglas was able to swim, dive, crawl and so on.

Important Questions for Class 12 English

The Last Lesson Important Questions CBSE Class 12 English

In this page, you can find The Last Lesson Extra Questions and Answers Class 12 English Flamingo

Short Answer Type Questions (3 Marks, 30-40 words)

Question.1. What tempted Franz to stay away from school? (Delhi 2014; Medtffot)
Answer. Franz feared a scolding at school as he had not prepared hte lesson on participles, on which his French teacher M Hamel was to question the class that day. Besides* the warm and bright weather, the chirping of birds and the watching the drill of Prussian soldiers also tempted Franz to stay away from school.

Question.2. What was unusual about M Hamel’s dress on his last day in the school?
(Compartment 2014)
Answer. M Hamel had put on his ceremonial clothes on his last day in the school. He was wearing a beautiful green coat, a frilled shirt, and a little black embroidered silk cap. This was a special ceremonial attire which he usually wore on days of inspection and prize distribution.

Question.3. Why is the order from Berlin called a thunderclap by Franz? (Compartment 2014)
or
“What a thunderclap these words were to me!” What were the words that shocked
and surprised the narrator? : (Delhi 2013)
Answer. M Hamel told his students that it was their last French lesson, as an order had come from Berlin that henceforth only German was to be taught in the schools of Alsace and Lorraine. This announcement seemed to be a thunderclap to Franz. He was left in surprise and shock to learn that a new master was going to arrive the next day and they would learn German instead of their mother tongue.

Question.4. Who were sitting on the back benches during M Hamel’s last lesson? Why? (Compartment 2014)
or
Why had the villagers come to school on the day of the last lesson? (Foreign 2008)
or
Why were the elders of the village sitting in the classroom? (Allindia 2014)
Answer. Some of the elderly people from the village were sitting on .the back benches during M Hamel’s last lesson. The villagers had come there to attend his last lesson as it was their way of paying respect to the master, who had given forty years of faithful service to the school.

Question.5. Why does M Hamel reproach himself for his students, unsatisfactory progress in
Studies? (Compartment 2014)
Answer. M Hamel had been rather irregular as a teacher. He took leave whenever he wanted to. Besides, he had often sent the students to water his plants, and whenever he wanted to go fishing, he just gave them a holiday. So, he reproaches himself for his students’ unsatisfactory progress in studies.

Question.6. What shows M Hamel’s love for the French language? (Foreign 2014)
or
What did M Hamel tell them about the French language? What did he ask them to
do and why? (Delhi 2013)
Answer. In his last lesson, M Hamel told the students that the French language was the most beautiful language in the world—the clearest and the most logical. He asked them to guard it amongst themselves and never forget it, because when a people were enslaved, as long as they held fast to their language, it was as if they had the key to their prison.

Question.7. What words did M Hamel write on the blackboard before dismissing the last class?
What did they mean? (Compartment 2014)
Answer. Before dismissing the last class, M Hamel turned to the blackboard, and wrote the phrase, ‘Vive La France!’ as large as he could. These words meant ‘Long live France’, and spoke of M Hamel’s great love for his country and his deep sense of patriotism.

Question.8. What made M Hamel cry towards the end of his last lesson? (Compartment 2014)
Answer. M Hamel had taught French at the school for the last forty years. He was emotionally attached to the school and everything in and about it. He was really heartbroken to leave it all. Besides, his own predicament reminded him that his country would soon lose its independence. All this made him cry towards the end of his last lesson.

Question.9. How did Franz react to the declaration that it was their last French lesson? (Delhi 2013)
or
What announcement did M Hamel make? What was the impact of this on Franz?
(All India 2011)
or
‘‘This is your last French lesson.” How did Franz react to this declaration of M Hamel? (Delhi 2010)
or
What changes came over little Franz after he heard M Hamel’s announcement?
(All India 2010)
or
What did the French teacher tell his students in his last French lesson? What impact did it have on them? (All India 2009)
Answer. The French teacher M Hamel announced that he would be teaching his last French lesson that day because the orders had come from Berlin to teach only German in the schools of Alsace and Lorraine. On hearing this, all the students as well as Franz felt very sorry that they would not be learning their mother tongue in future. Franz regretted not having learnt his lessons. Earlier his books seemed a nuisance to him, but at that moment they became very dear to him.

Question.10.What was the order from Berlin and what changes did it cause in the school?
(AU India 2013)
or
What changes did the order from Berlin cause in the school? (Delhi 2012)
or
What was the mood in the classroom when M Hamel gave his last French lesson?
(Delhi 2009)
Answer. The order from Berlin stated that only German will be taught in the schools of Alsace and Lorraine. The order effected many changes, as an unusual silence prevailed in the school, compared to the hustle and bustle earlier. M Hamel became soft in speaking to the students, while the people realised the importance of their language. The villagers even attended the school to show respect to M Hamel.

Question.11. How did M Hamel say farewell to his students and the people of the town?
(All India 2012)
Answer. At the end of his ‘Last Lesson’,. M Hamel stood up to say farewell to his students and the people of the town. He tried to speak, but overwhelming emotion choked his voice. He then wrote as large as he could on the blackboard ‘Vive La France’; then he dismissed the class with a gesture with his hand.

Question.12. What was Franz expected to be prepared with for the school that day? (Delhi 2011)
Answer. Franz was expected to be prepared with participles that day. His teacher M Hamel, was to question him on the topic. Franz had not learnt his lessons and feared to be scolded by him.

Question.13. What had been put up on the bulletin-board? (Delhi 2011)
Answer. Since the last two years the bulletin-board had news of lost battles, the draft and the orders of the commanding officer. On that day a notice had been put up stating that orders from Berlin were to teach only German in the schools of Alsace and Lorraine.

Question.14. Who did M Hamel blame for the neqlect of leaminq on the part of boys like Franz?
(Delhi 2011)
Answer. M Hamel blamed himself for the neglect of learning on the part of boys like Franz. He himself was not quite regular and took leave whenever he needed it, which reflected on the behaviour and studies of the students. He also blamed their parents for not taking mterest in their education.

Question.15. Franz thinks, “Will they make them sing in German, even the pigeons?” What does
this tell us about the attitude of the Frenchmen? (All India 2011)
Answer. This shows that the Frenchmen were full of hatred and desperation against the Germans. Besides, they feared German atrocities. They thought that they would be forced to read German and no one will be spared.

Question.16. Mention two thingsLabout M Hamel that surprised Franz on his last day at school.
(Foreign 2009)
Answer. M Hamel didn’t scold Franz for being late; instead he told him very kindly to go to his place. Also, that day he was dressed in his best clothes; he was in his beautiful green coat, frilled shirt and little black silk cap with embroidery, which he wore only on inspection or prize days.

Question.17. How was the scene in the school in the morning of the last lesson different from that
on other days? (Delhi 2008)
Answer. Usually, there used to be great hustle and bustle when the school began. The din of opening and closing of the desks, lessons being repeated in unison and the rapping of the teacher’s ruler on the table, could be heard out in the street. But that day, it was all very quiet and still as on a Sunday morning.

Long Answer Type Question (6 Marks, 120-150 words)

Question.1. What changes did the narrator find in the school when the order from Berlin came?
(Ail India 2008)
Answer. The order from Berlin prohibited teaching of French in the schools of Alsace and Lorraine. Instead, German was to be taught in the schools. Franz was late for school that day. He noticed that the hustle and bustle was missing. There was no opening and closing of desks, no repetition of lessons or rapping of the teacher’s ruler on the table could be heard. It was all very quiet and still.
Franz was further surprised because, instead of meeting an angry teacher, he was welcomed by a kind and polite teacher, who was dressed in his best clothes, a beautiful green coat, frilled shirt and an embroidered silk cap, which he wore only on inspection and prize days. The back benches were occupied by the village people who never came to school, as they were more concerned about their livelihood. He was further astounded to know that , M Hamel was going to teach his last lesson that day.

Important Questions for Class 12 English

CBSE Previous Year Solved  Papers  Class 12 Maths Outside Delhi 2011

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

SECTION – A

SECTION – B

SECTION – C

SET II

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

SECTION – A

SECTION – B

SECTION – C

SET III

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

SECTION – A

SECTION – B

SECTION – C

CBSE Previous Year Solved  Papers  Class 12 Chemistry Delhi 2011

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.‘Crystalline solids are anisotropic in nature’. What does this statement mean?
Answer : It means that some of the physical properties of crystalline solids such as refractive index, electrical conductivity, thermal expansion, etc. show different values when measured along different directions in the same crystal.

Question.2.Express the relation between conductivity and molar conductivity of a solution held in a cell.
Answer : The molar conductivity of a solution is related to conductivity of that solution as :

Question.3.Define ‘Electrophoresis’.
Answer: Electrophoresis is the phenomenon of movement of colloidal particles under the applied electric field.

Question.4.What is the structure of XeF₂ molecule? Draw it.
Answer:

Question.5.Write the IUPAC name of the following compound : (CH₃)₃CCH₂Br
Answer: l-bromo-2, 2-dimethylpropane

Question.6.Draw the structure of 3-methylbutanal.
Answer:

Question.7.Arrange the following compounds in an increasing order of their solubility in water:

Question.8.Biodegradable polymers.
Answer : Bio-degradable polymers are natural polymers that disintegrated themselves over a period of time by enzymatic hydrolysis, e.g. starch, cellulose, etc.

Question.9.The chemistry of corrosion of iron is essentially an electro-chemical phenomenon. Explain the reactions occurring during the corrosion of iron in the atmosphere.
Answer : According to electrochemical theory of rusting, the impure iron surface behaves like small electrochemical cell in the presence of water containing dissolved oxygen or carbon dioxide. In this cell pure iron acts as an anode and impure iron surface acts as cathode. Moisture having dissolved CO₂ or O₂  acts as an electrolyte. The reactions at cathode and anode are as follows :

Question.10. Determine the values of equilibrium constant (K_c) and ΔG° and for the following reaction :

Question.11. Distinguish between ‘rate expression’ and ‘rate constant’ of a reaction.
Answer : Rate constant is the rate of reaction when the concentration of each reactant is taken as unity.
Rate expression expresses the rate fef reaction in terms of molar concentrations of the reactants with each term raised to their power, which may or may not be same as the stoichiometric coefficient of that reactant in the balanced chemical equation.

Question.12. Give reason for :

1.  The N-O bond in NO^–₂is shorter than the N-O bond in NO^–₃
2. SF₆ is kinetically an inert substance.

OR
State reasons for each of the following:

1. All the P-Cl bonds in PCl₅ molecules are not equivalent.
2. Sulphur has greater tendency for catenation than oxygen.

Answer :

1. The resonating structure of NO^–₂shows that NO₂ two bonds are sharing double bond while in NO^–₃ three bonds are sharing a double bond. Thus, NO^–₂ has shorter bond than that of NO^–₂ .
   Resonating structure of NO^–₂ and NO^–₃.
   
2. SF₆ is kinetically inert due to high oxidizing power and electronegativity of fluorine atom which causes steric hindrance and it unable to react further with any other atom.

OR

1.  It is because all bonds are not in same plane. Three P-Cl equatorial bonds are in one plane whereas two axial bonds are in vertical plane which are longer than equatorial bonds.
   
2. Sulphur has a much greater tendency for catenation than oxygen because of its bigger size and low electronegativity due to which the S-S bond is stronger than 0-0 bond and there is more interelectronic repulsion in 0-0 than in S-S bond.

Question.13. Assign reasons for the following:

1. Copper (I) ion is not known in aqueous solution.
2.  Actinoids exhibit greater range of oxidation states than lanthanoids.

Answer:

1.  In aqueous solution Cu+ undergoes disproportionation to form a more stable Cu²⁺ ion.
   2Cu⁺(aq) → Cu²⁺(aq) + Cu(s)
   The higher stability of Cu²⁺ ion is aqueous solution may be attributed to its greater negative  Δ_hydH than that of Cu⁺ion. It compensates the second ionisation enthalpy of Cu involved in the formation of Cu²⁺ions.
2. Actinoids exhibit greater range of oxidation states than lanthanoids. This is because there is less energy difference between 5d and 6d orbitals belonging to actinoids than the energy difference between 4d and 5d orbitals in case of lanthanoids.

Question.14.Explain the following giving one example for each :

1. Reimer-Tieman reaction.
2. Friedel Craft’s acetylation of anisole.

Answer :

1.  When phenol is treated with chloroform in presence of aqueous NaOH at 340 K followed by hydrolysis gives salicylaldehyde.
   
2.  When anisole is treated with acetylchloride in presence of anhydrous AlCl₃, 2-methoxy acetophenone is formed.
   

Question.15. How would you obtain :
(i) Picric acid (2,4, 6-Trinitrophenol) from phenol.
(ii)2-Methylpropene from 2-methylpropanol?
Answer:

Question.16. What is essentially the difference between a-form of glucose and p-form of glucose? Explain.
Answer : In a-form of glucose OH group lies at Cl towards right but in P-form of glucose it is towards left. This is because OH group at Cl in glucose is chiral.

Question.17. Describe what you understand by primary structure and secondary structure of proteins.
Answer : Primary structure of proteins refer to the*sequence in which amino acids are joined together by peptide linkage. The sequence of amino acids in primary structure is very specific. Any change in the sequence of amino acids creates a different protein with different biological activity.
Secondary structure of proteins refers to the conformation which arises due to the coiling of polypeptide chain due to intramolecular hydrogen bonding between carbonyl and —NH groups. Depending upon the size of -R group, there are two secondry structures of pfotein, i.e. a -Helix and p -Pleated sheet like structure.

Question.18. Mention two important uses of the following

1.  Bakelite
2. Nylon-6

Answer: Bakelite: It is used in the manufacture of electrical switches, protective coatings, barrels, etc.
Nylon-6 : It is used in making Fabrics, tyre cords, mountaineering ropes etc.

Question.19. Silver crystallizes in face-centered cubic unit cell. Each side of this unit cell has a length of 400 pm. Calculate the radius of the silver atom. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. That is each face atom is touching the four comer atoms).

Question.20. Nitrogen pentoxide decomposes according to equation :

(i) Calculate the rate constant. Include units with your answer.
(ii)What will be the concentration of N₂O₅ after 100 minutes?
(iii)Calculate the initial rate of reaction.
Answer. (i) We Know that

Question.21. Explain how the phenomenon of adsorption finds application in each of the following processes :

1. Production of vacuum
2. Heterogeneous catalysis
3. Froth Floatation Process

OR
Define each of the following terms :

1.  Micelles
2. Peptization
3. Desorption

Answer :

1. In vacuum flasks, activated charcoal is placed between the walls of the flask so that any gas which enters into annular space either due to glass imperfection or diffusion through glass is adsorbed and create a vacuum.
2. If the catalysts and reactants are present in different phase, the process of catalysis is called as heterogenous catalysis. For example, manufacture of NH₃ from N₃ and H₂ by Haber’s process using iron as catalyst
   
   In this process, the-reactants are in gaseous phase whereas catalyst is in solid phase. *
3. This method is used for removing gangue from sulphide ores. In this powdered ore is mixed with collectors (e.g. pine oil, fatty acids etc.) and froth stabilizers (e.g. cresols, aniline) which enhance non-wet ability of the mineral particles and froth stabilisation respectively. As a result of which ore comes with froth and gangue remain in the solution.
   

 

1. When soaps and detergents are added to water, a cluster of charged particle is formed by the aggregation of variety of molecules. Thus formed is called micelle.
2. The process of converting a fresh precipitate into colloidal particles by shaking it with the dispersion medium in the presence of a small amount of a suitable electrolyte is called peptization.
3. The process of removal of adsorbed substance from the surface of a solid or a liquid by heating or by reducing pressure is called desorption.

Question.22. Describe the principle behind each of the following
processes:

1.  Vapour phase refining of a metal.
2. Electrolytic refining of a metal
3. Recovery of silver after silver ore was leached with NaCN.

Answer :

1. Vapour Phase refining: The impure metal is first converted to its unstable volatile compound which is evaporated and then decomposed by heating at higher temperature to give pure metal, leaving behind the impurities.
2. In this method impure metal is made anode and a thin sheet of pure metal is made cathode, and are put in a suitable electrolyte containing soluble salt of same metal. On passing current the more basic metal remains in the solution and the less basic one go to the anode and gets deposited as anode mud.
3. NaCN acts as a leaching agent or oxidizing agent, thus oxidize Ag to Ag⁺  which then combine with CN^–  ions to form respective soluble complex.
   

Question.23.Complete the following chemical equations :

Question.24. Write the name, stereochemistry and magnetic behaviour of the following:

Question.25. Answer the following:
(i) Haloalkanes easily dissolves in organic solvents, why?
(ii)What is known as a racemic mixture? Give an example.
(iii)Of the two bromoderivatives, C₆H₅CH(CH₃)Br and C₆H₅CH( C₆H₅)Br, which one is more reactive in SNI substitution reaction and why?
Answer :
(i) Haloalkanes dissolve in organic solvents because the new intermolecular attraction between haloalkanes and organic solvent molecules have the same strength as the one being broken in the separate haloalkanes and solvent molecules.
(ii) Racemic mixture is an equimolar mixture of two enantiomers and is hence optically inactive, e.g. (± butan-2-ol)

Question.26. (a) Explain why an alkylamine is more basic than ammonia?
(b) How would you convert:
(i) Aniline to nitrobenzene
(ii)Aniline to iodobenzene
Answer :
(a) Alkyl groups are electron donating groups and increase the electron density on nitrogen in alkylamine making them more basic than ammonia.

Question.27. Describe the following giving one example for each :

1. Detergents
2. Food preservatives
3. Antacids

Answer :

1. Detergents are soluble salts of sodium potassium sulphonic acids unlike soaps they are non-biodegradble but they can be conveniently used both with soft and hard water. e.g. Sodium alkylbenzene sulphonate.
2. Food preservatives are chemicals used to preserve food by preventing microbial growth e.g. Sodium benzoate, Table salt, etc.
3. The substances which are taken to neutralize the excess acid and maintaining the pH to an appropriate level in stomach are called antacids. There are two types of anatacids systemic antacids, e.g, NaHCO₃ and non-systemic e.g. Milk of magnesia.

Question.28. (a) Differentiate between molality and molarity of a solution. How does a change in temperature influence their values?
(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr₂  in 200 g of water. (Molar mass of MgBr₂ = 184 g) (K_ƒ for water = 1.86 K kgmol^-1
OR
(a) Define the terms osmosis and osmotic pressure. Is the osmotic pressure of a solution a colligative property? Explain
(b) Calculate the boiling point of a solution prepared by adding 15.00 g of NaCl to 250.0 g of water. (K_b for water = 0.512 K kg mol^-1, Molar mass of NaCl = 58.44 g)
Answer:
(a) Molarity is the number of moles of solute dissolved in 1 litre of solution. It is temperature dependent.

Molality is the number of moles of solute dissolved per 1 kg of the solvent. It is temperature independent.

Molality is independent of temperature, whereas molarity is a function of temperature because volume depends on temperature and mass does not.
(b) Since MgBr₂ is an isotonic compound. Hence undergoes complete dissociation

(a) Osmosis is the phenomenon of flow of solvent through a semi-permeable membrane from the region of higher concentration to the region of lower concentration.
The osmotic pressure of a solution is the excess pressure that must be applied to the solution to prevent the passage of solvent molecule through a semi-permeable membrane into the solution.
Yes, osmotic pressure is a colligative property as it depends only on the amount of solute present in the solution.
(b) Initial moles after dissociation we know that,

Question.29. Give chemical tests to distinguish between:
(i) Propanal and propanone
(ii)Benzaldehyde and acetophenone (b) How would obtain :
(i) But-2-enal from ethane
(ii)Butanoic acid from butanol
(iii)Benzoic acid from ethylbenzene
OR
(a) Describe the following giving linked chemical equations
(i) Cannizzaro reaction
(ii)Decarboxylation
(b) Complete the following chemical equations :

Question.30. (a) Explain the foUowing:
(i) NF₃ is an exothermic compound whereas NCl₃ is not.
(ii)F₂is most reactive of all the four common halogens,
(b) Complete the following chemical equations:

(a) Account for the following :
(i) The acidic strength decreases in the order HCl > H₂S > PH₃
(ii)Tendency to form pentahalides decreases down the group in group 15 of the periodic table.
(b) Complete the following chemical equations :

Answer : (a) (i) Due to smaller size of F as compared to Cl, the N-F bond is much stronger than N-Cl bond while bond dissociation energy of F₂ is much lower than that of Cl₂. Therefore, energy related during the formation of NF₃ molecule is more than the energy needed to break N₂ and F₂ molecules into individual atoms. In other words, formation of NF₃ is an exothermic reaction.
The energy released during the formation of NCl₃ molecule is less than the energy needed to break N₂ and Cl₂ molecule into individual atoms. Thus, formation of NCl₃ is an endothermic reaction.
(ii) Fluorine is most reactive of all the four common halogens because of is low bond dissociation energy due to which it readily dissociates into atoms and reacts with other substances readily

(a) (i) Because of decrease in electronegativity from chlorine to phosphorus, the dissociation enthalpy from HCl to H-P increases, and their tendency to release H⁺ ion decreases and thus acidic strength decreases.
(ii) This is due to inert pair effect. The stability of +5 oxidation state decreases down the group in group 15.

SET II

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

Question.1. Which stoichiometric defect in crystals decreases the density of a solid?
Answer : Schottky defect.

Question.3. What is meant by shape-selective catalysis of reactions?
Answer: The reaction that depend for shape selective catalysts uses zeolites as catalyts for reaction on the shape and size of pores and of reactants and products.

Question.4. Draw the structure of XeF₄ molecule
Answer:

Question.9. Explain what is meant by

1.  a peptide linkage,
2. a glycosidic linkage?

Answer :

1.  Peptide linkage is present in proteins to bind together amino acids. The linkage involves the carboxyl group of one amino acid and amine group of another amino acids,
2. Glycosidic linkage is the (-C-O-C-) linkage present between two molecules of a monosaccharide to form a disaccharide.

Question.10. Name the bases present in RNA. Which one of these is not present in DNA.
Answer : Four bases present in RNA are adenine, guanine, Cytosine and Uracil.

Question.22. Explain the role of each the following in the extraction of metals from their ores :
(i) CO in the extraction of nickel.
(ii) Zinc in the extraction of silver.
(iii) Silica in the extraction of copper.

Question.24. For the complex [Fe(en)₂Cl₂], identify the following:

1. Oxidation number of iron.
2. Hybrid orbitals and shape of the complex
3. Magnetic behaviour of the complex
4. Number of its geometrical isomers.
5.  Whether there may be optical isomer also.
6. Name of the complex.

Answer:

1. +3
2. Sp³d²,octahedral shape.
3. paramagnetic
4. 2 geometrical isomers, cis and trans.
5.  Only cis-isomers shows optical isomerisrrt
6. Dichloridobis (ethylenediamine) iron(III) chloride

Question.27. Explain the following terms with one suitable example for each:

1. A sweetening agent for diabetic patients
2. Enzymes
3. Analgesics

Answer :

1.  Artificial sweeting agent are chemicals that sweeten food. However, unlike natural sweetners, they do not add calories to our body, not harmful to diabtic patients, e.g. Saccharin, aspartame.
2. Enzymes are biocatalysts which are structurally globular proteins. They are sensitive to substrate, pH and temperature changes, e.g. Trypsin
3. Analgesics are chemical substances which reduces pain
   without causing impairment of consciousness, mental confusion, in coordination of paralysis or some other disturbance of nervous system, e.g. Aspirin, (non-narcotic analgesic) and morphine (narcotic analgesic)

Question.28. (a) State the following:

1.  Henry’s law about partial pressure of a gas in a mixture.
2. Raoult’s law in its general form in reference to solutions.

(b) A solution prepared by dissolving 8.95 mg of a gene fragment in 35.0 mL of water has an osmotic pressure of 0.335 torr at 25°C. Assuming the gene fragment is non-electrolyte, find its molar mass.
OR
(a) Difference between molarity and molality in a solution. WTiat is the effect of temperature change on molarity and molality in a solution?
(b) What would be the molar mass of a compound if 6.21 g of it dissolved in 24.0 g of chloroform form a solution that has a boiling point of 68.04°C. The boiling point of
pure chloroform is 61.7°C and the boiling point elevation constant, for chloroform is 3.63°C/m.
Answer : (a)

1. Henry’s law states that the partial pressure of gas in vapour phase is directly proportional to its mole fraction in the solution,
2.  Raoults law states that for a solution with volatile components, the partial vapour pressure of each component present in the solution is proportional to its mole fraction in the solution.

OR
(a) Molarity is defined as the number of moles of solute present in 1 litre of solution, while molality is defined as the number of moles of solute present in 1 kg of solvent. Molality does not have any effect of change in temperature because mass does not change with temperature, whereas molarity changes with temperature.

SET III

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

Question.4. Draw the structure of BrF₃ molecule

Question.8. In nylon 6, 6 what does the designation ‘6,6’ mean?
Answer: 6,6-refers to the number of carbon atoms in each of its monomer, adipic acid and hexamethyldiamine

Question.9.What type of a battery is lead storage battery? Write the
anode and the cathode reactions and the overall reactions occurring in a lead storage battery.
Answer : The lead storage battery is a secondary cell which is rechargeable. During discharging, the electrode reaction occurs as follows :
At anode:

Question.10. The half-reactions of an electrochemical cell are given below:

Question.13. Assign reasons for each of the following:

1.  Transition metals generally form coloured compounds.
2. Manganese exhibits the highest oxidation state of +7 among the 3d series of transition elements.

Answer :

1. Due to presence of unpaired electrons and d-d transition, the transition metals are generally coloured.
2.  Manganese (z = 25), has the maximum number of unpaired electrons. Thus, it shows oxidation states from +2 to +7 which is maximum in number as compared to other elements of transition series.

Question.18. Name the sub-groups into which polymers are classified on the basis of magnitude intermolecular forces.
Answer : Elastomers : They have weakest intermolecular forces of attraction.
Fibres : They have strong intermolecular forces of attraction among its molecules.
Thermoplastics Polymers : They are semifluid substances having low molecular weight.
Thermosetting polymers – They have intermolecular. forces intermediate between those of elastomers and fibres.

Question.19. The density of lead is 11.35 g cm^-3 and the metal crystallizes with fee unit cell. Estimate the radius of lead atom. (At.mass of lead = 207 g mol^-1 and N_A = 6.02 x 10²³ mol^-1)

Question.26. Complete the following chemical equations :

Answer:

Question.27. Answer the following questions :

1. Why do soaps not work in hard water ?
2. What are the main constituents of dettol?
3. How do antiseptics differ from disinfectants?

Answer :

1. Hard water contains insoluble chloride of calcium and magnesium which form insoluble ppt. (scum) with soap and thus cannot be rinsed off easily.
2. The main constituents of dettol are chloroxylenol and a-terpine.
3. Antiseptics : These are chemical substances which either kill or prevent the growth of micro-organism but do not cause harm to the living tissues.
   Disinfectants : These are chemical substances which kill the  microbes. They are toxic in nature and thus cause harm to the tissues of the skin

CBSE Previous Year Solved  Papers  Class 12 Maths Delhi 2011 

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 questions have been asked in previous Sets.

SECTION – A

1. State the reason for the relation R in the set {1,2,3} given by R = {(1,2), (2,1)} not to be transitive.

SECTION – B

11. Consider the binary operation * on the set {1, 2, 3, 4, 5} defined by a* b = min. {a, b). Write the operation table of the operation *.

16. Sand is pouring from a pipe at the rate of 12 cm³/s. The falling sand forms a cone on the ground in such a way that the height of the cone is always one-sixth of the radius of the base. How fast is the height of the sand cone increasing when the height is 4 cm ?
Solution: Let r be the radius, h be the height and V be the volume of the sand cone.

Find the points on the curve x² + y² 2x-3 = 0at which the tangents are parallel to x-axis.
Solution: When the tangent is parallel to x-axis

22. Probabilities of solving a specific problem independently by A and B are 1/2 and 1/3 respectively. If both try to solve the problem independently, find the probability that
(i) the problem is solved
(ii) exactly one of them solves the problem.
Solution: Given,

SECTION – C

24. Show that of all the rectangles inscribed in a given fixed circle, the square has the maximum area.
Solution : Let length of rectangle be x and breadth of rectangle be y.

28. A factory makes tennis rackets*,and cricket bats. A tennis racket takes 1.5 hours of machine time and 3 hours of craftsman’s time in its making while a cricket bat takes 3 hours of machine time and 1 horn1 of craftsman’s time. In a day, the factory has the availability of not more than 42 hours of machine time and 24 hours of craftsman’s time. If the profit on aracket and on a bat is Rs 20 and Rs  10 respectively, find the number of tennis rackets and circket bats that the factory must manufacture to earn the maximum profit. Make it as an L.P.P. and solve graphically.
Solution: Let x be the number of tennis rackets and y that of cricket bats produced in one day in the factory.

29. Suppose 5% of men and 0.25% of women have grey hair. A grey haired person is selected at random. What is the probability of this person being male ? Assume  that there are equal number of males and females.

SET II

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

SECTION – A

SECTION – B

15. Formthe differential equation of the family of parabolas having vertex at the origin and axis along positive y- axis

SECTION – C

23. Bag I contains 3 red and 4 black balls and Bag II contains 5 red and 6 black balls. One ball is drawn at random from one of the bags and is found to be red. Find the probability that it was drawn from Bag II.
Solution:

SET III

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

SECTION – A

SECTION – B

SECTION – C

23. A man is known to speak truth 3 out of 4 times. He throws a die and reports that it is a six. Find the probability that it is actually a six.
Solution: Let E be the event that the man reports that six occurs in the throwing of a die and let S₁ be the event that six occurs and S₂ be the event that six does not occur,

CBSE Sample Papers for Class 8 Science Practice Paper 1

Test Paper I
Class VIII

Time : 2 1/2 Hrs                                                                                               Maximum Marks : 100                                                                                                     

General Instructions:

1. Read the content of the question carefully and attempt them there after.
2. Follow the specified word limit, wherever mentioned.
3. Try to be brief and concise and have clarity in expression.
4. Make diagrams and figures wherever necessary.

1. Fill in the blanks:                                                                                                                    1 x 10 = 10

1. Reserve stock of food grains of a country is called………..
2. The process of cutting and gathering a crop is known as………..
3. ………..is a dreaded disease of cattle, sheep and goats.
4. Stomach produces………..acid to kill microbes.
5. Disease causing microbes are called………..
6. Mushrooms are edible………..
7. The hardest known material is………..
8. Chemical action in metals exposed to air and water is called………..
9. A………..has a distinct head and a glowing tail.
10. ………..is used in rockets to oxidise rocket fuel.

2. Give one word answer                                                                                                           1 x 10 = 10

1. A homogeneous mixture of two or more metals and non metals.
2. Name the first satellite launched by India.
3. Groups of stars arranged in interesting patterns.
4. A non-metal, generally used as rat poison.
5. Rearing and management of silk moths.
6. Diseases which spread fast in an area and take a heavy toll of human life.
7. The resistance created in our body to fight infection.
8. The process by which milk products are generally preserved.
9. The study of Carbon and its compounds.
10. Cell organell often called suicide bags.

3. Do as directed:

1. What happens when (write only chemical equation)                                                       1 x 3 = 3
   (a) Sodium react with hydrochloric acid.
   (b) Magnesium react with water.
   (c) Zinc react with Sulphuric acid.
2. Name the two alloy of:                                                                                                         1 x 3 = 3
   (a) Ee                          (b) Cu                                (c) Al
3. Name two breeds of:                                                                                                            1 x 3 = 3
   (a) Wheat                  (b)Rice                              (c) Cow
4. Write two name of:                                                                                                               1 x 3 = 3
   (a) Heavy metals     (b) Protective metals      (c) Radioactive

4. Write short notes on:                                                                                                             2 x 5 = 10

1. Transplantation
2. Corrosion and its effects
3. Irrigation
4. Electroplating
5. Acid rain and its harms

5. Give the answer of the following questions:                                                                 3 x 10=30

1. What is magnetic induction?
2. What is an electromagnet? Name two application of an electromagnets.
3. What are micro-organism? Name the different types of micro-organism.
4. What are chromosomes? Where can you find them in a cell?
5. Name the three methods to prevent corrosion of metals.
6. Describe some ways by which we can reduce air pollution.
7. What is a light year? How many light years is the sun away from Earth?
8. What is hybridisation?
9. What are harmful effects of pesticides?
10. Write three uses of Copper and Zinc.

6. Differentiate between the following pairs with examples (any three)                4 x 3 = 12

1. Macronutrients and micronutrients.
2. Communicable and non-communicable diseases.
3. Metals and Non-metals.
4. Rabi and Kharif crops.

7. Write answer in detail: (Any two)                                                                                     5 x 2 = 10

1. What are two methods of making a temporary magnet? Explain with diagram.
2. What is Green Revolution? List the agricultural practices that have resulted in the green revolution.
3. What is a reactivity series of metals? Write name of metals according to series.

8. Draw labelled diagram of any one part:                                                                                         6

1. An electromagnet and magnetic compass.
2. Bacteriophage and Ursa major.