Category: CBSE

Looking for an easy way to Learning of new elementary english grammar and composition for class 7 answers, Solutions. You have to learn basic English Grammar topics like Tenses Verbs, Nouns, etc… In this article, we will review the best English Grammer Topics and compare them against each other.

Third Conditional Sentences Exercises for Class 7 With Answers CBSE Pdf

We make the third conditional by using the past perfect after ‘if’ and then ‘would have’ and the past participle in the second part of the sentence:
Formation:
if + past perfect, …would + have + past participle

It talks about the past. It’s used to describe a situation that didn’t happen, and to imagine the result of this situation.
Examples:

• If she had studied, she would have passed the exam, (but, really we know she didn’t study and so she didn’t pass)
• If I hadn’t eaten so much, I wouldn’t have felt sick, (but I did eat a lot, and so I did feel sick).
• If we had taken a taxi, we wouldn’t have missed the plane.
• She wouldn’t have been tired if she had gone to bed earlier.
• She would have become a teacher if she had gone to university.
• He would have been on time for the interview if he had left the house at nine.

Presentations:
Read the picture story.

Answer the following questions.
1. How would players have scored more goals?
2. When would Referee have awarded a penalty kick?
3. How would game have become better?

Third Conditional Sentences Exercises With Answers for Class 7 CBSE

A. Complete the Third Conditional by putting the verbs into the correct form. The first one has been done for you.

1. If you (study) had studied for the test, you (pass) would have passed it.
2. If you (ask) _____________ me, I (help) _____________ you.
3. If we (go) _____________ to the cinema, we (see) _____________ my friend Jatin.
4. If you (speak) _____________ English, she (understand) _____________.
5. If they (listen) _____________ to me, we (be) _____________ home earlier.
6. I (write) _____________ you a postcard if I (have) _____________ your address.
7. If I (not/break) _____________ my leg, I (take part) _____________ in the contest.
8. If it (not/start) _____________ to rain, we (walk) _____________ to the museum.
9. We (swim) _____________ in the sea if there (not/be) _____________ so many sharks there.
10. If she (take) _____________ the bus, she (not/arrive) _____________ on time.

B. Put the words in brackets into the correct form to make third conditional sentences.

1. If I (pass) _____________ my driving test last month, I would have bought a car straight away.
2. If I (complain) _____________ in the shop, they might have given me a discount.
3. The job (be done) _____________ much faster if there’d been more people helping. As it was, it took us forever.
4. If the job (not/take) _____________ so long, we would’ve had more time to do other things.
5. I (not/say) _____________ what I said if I had known earlier what her reaction was going to be.
6. I wouldn’t have bought the house if I (know) _____________ it had plumbing issues.
7. If I (be) _____________ in your shoes, I wouldn’t have accepted the offer. You made a big mistake.
8. I (not/start) _____________ the job if I had known it was going to take so long.

Looking for an easy way to Learning of new elementary english grammar and composition for class 7 answers, Solutions. You have to learn basic English Grammar topics like Tenses Verbs, Nouns, etc… In this article, we will review the best English Grammer Topics and compare them against each other.

First Conditional Sentences Exercises for Class 7 With Answers CBSE Pdf

The first conditional has the simple present after ‘if’, then the future simple in the other clause.
Formation:
if + simple present,… will + infinitive

It’s used to talk about things which might happen in the future. Of course, we can’t know what will happen in the future, but this describes possible things, which could easily come true.
Examples:

• If it rains, I won’t go to the park.
• If I study today, I’ll go to the party tonight.
• If I have enough money, I’ll buy some new shoes.
• She’ll be late if the train is delayed.
• She’ll miss the bus if she doesn’t leave soon.
• If I see her, I’ll tell her.

Presentation:
Read the picture story.
Answer the following questions.
1. What are the three duties of Mita?
2. When will Ritu and Pooja make sandwiches?
3. How will the party be great?

First Conditional Sentences Exercises With Answers for Class 7 CBSE

A. Complete the Conditional Sentences (First Conditional) by putting the verbs into the correct form.

1. If you (send) send this letter now, she (receive) will receive it tomorrow.
2. If I (do) __________ this test, I (improve) __________ my English.
3. If I (find) __________ your ring, I (give) __________ it back to you.
4. Payal (go) __________ shopping if she (have) __________ time in the afternoon.
5. Sameer (go) __________ to London next week if he (get) __________ a cheap flight.
6. If her boyfriend (phone/not) __________ today, she (leave) __________ him.
7. If they (study/not) __________ harder, they (pass/not) __________ the exam.
8. If it (rain) __________ tomorrow, I (have to/not) __________ water the plants.
9. You (be able/not) __________ to sleep if you (watch) __________ this scary film.
10. Suman (can/move/not) __________ into the new house if it (be/not) __________ ready on time.

B. Complete the conditional sentences (First Conditional). Remember to use the auxiliary verbs.

1. If it doesn’t rain, we (can/go) __________ swimming tomorrow.
2. If you train hard, you (might/win) __________ the first prize.
3. If we go to Canada next year, we (can/work on) __________ our English.
4. I (may/go) __________ to the disco in the evening if I do the laundry now.
5. If we go on holiday next week, I (not/can/play) __________ tennis with you.
6. If you see Ganesh tomorrow, you (should/tell) __________ him that you love him.
7. If my parents go shopping in the afternoon, I (must/look) __________ after my little sister.
8. He (must/be) __________ a good drummer if he plays in a band.
9. If you are listening to the radio after 10 pm, you (should/turn) __________ volume down.
10. If you like that shirt, you (can/have) __________ it.

C. Write the correct first conditional form of the verbs given in the brackets.

1. If I __________ (go) out tonight, I __________ (go) to the cinema.
2. If you __________ (get) back late, I __________ (be) angry.
3. If we __________ (not/see) each other tomorrow, we __________ (see) each other next week.
4. If he __________ (come), I __________ (be) surprised.
5. If we __________ (wait) here, we __________ (be) late.
6. If we __________ (go) on a holiday this summer, we __________ (go) to Spain.
7. If the weather __________ (not/improve), we __________ (not/have) a picnic.
8. If I __________ (not/go) to bed early, I __________ (be) tired tomorrow.
9. If we __________ (eat) all this cake, we __________ (feel) sick.
10. If you __________ (not/want) to go out, I __________ (cook) dinner at home.

D. Fill in the boxes such that the sentences are in first conditional form.

1. If I __________ (to study), I __________ (to pass) the exams.
2. If the sun __________ (to shine), we __________ (to walk) into town.
3. If he __________ (to have) a temperature, he __________ (to see) the doctor.
4. If my friends __________ (to come), I __________ (to be) very happy.
5. If she __________ (to earn) a lot of money, she __________ (to fly) to New York.
6. If we __________ (to travel) to London, we __________ (to visit) the museums.
7. If you __________ (to wear) sandals in the mountains, you __________ (to slip) on the rocks.
8. If Rita __________ (to forget) her homework, the teacher __________ (to give) her a low mark.
9. If they __________ (to go) to the disco, they __________ (to listen) to loud music.
10. If you __________ (to wait) a minute, I __________ (to ask) my parents.

CBSE Notes for Class 8 Computer in Action – Exploring More Features of Adobe Photoshop

In the previous chapter, we learnt about the Selection tools, the Drawing tools and the Painting tools. In this chapter, we will learn about the Retouching tools and the Type tools. We will also learn about two interesting and useful features of Photoshop—Layers and Filters. Layers let us organise our work while Filters let us enhance the look of an image by adding various effects.

RETOUCHING TOOLS
The Retouching tools let you repair damaged images, apply repeated patterns or enhance the look of an image using various effects. Some of the Retouching tools available in Photoshop are Healing Brush Tool, Spot Healing Brush Tool, Patch Tool, Red Eye Tool, Blur Tool, Sharpen Tool, Smudge Tool, Dodge Tool, Sponge Tool, Burn Tool, Clone Stamp Tool and Pattern Stamp Tool.
Let us learn about some of these tools in detail.

The Healing Brush Tool allows you to repair imperfections such as scratches, blemishes and marks in an image. While working with this tool, you pick up sample pixels (pixels to be used for repairing) from the adjoining portion of an image. The Healing Brush Tool matches the texture, lighting, transparency and shading of the sampled pixels and applies them to the pixels that are being repaired.

The steps to use the Healing Brush Tool are:
Step 1: Select the Healing Brush Tool.
Step 2: Select the appropriate options for the Healing Brush Tool in the Options bar (Fig. 8.1).

These options include:

• Brush Picker: To set the size of the brush tip.
• Source: To specify whether to pick up sampled pixels from the image (Sampled) or use pre-defmed patterns.
• Aligned: To specify the sampling point to be used for repairing. If you select this option, you can release the mouse button without losing the current sampling point. If you deselect this option, the sampled pixels are always taken from the initial sampling point.

Step 3: Hold down the Alt key. The cursor shape changes to a target symbol. Click on the area close to the area to be repaired to pick up the sampled pixels.
Step 4: Click and drag over the area to be repaired. The image gets repaired (Fig. 8.2 and Fig. 8.3).


The Spot Healing Brush Tool works in a similar manner to the Healing Brush Tool except that it does not require the sampling point to be set. It automatically picks up the sampled pixels from around the area to be retouched. This tool can be used to quickly remove spots, blemishes and other marks from photographs.
The steps to use the Spot Healing Brush Tool are:
Step 1: Select the Spot Healing Brush Tool.
Step 2: Select the appropriate options in the Options bar (Fig. 8.3). One of the options includes choosing an appropriate Type option.

The Type options include:
(a) Content-Aware: Choosing this option uses actual content from the image close to the flaw. You can use this option when removing large items such as scratches from your image.
(b) Create Texture: Choosing this option uses all the pixels in the selection to create a texture that can be used to fix the area.
(c) Proximity Match: Choosing this option makes the Spot Healing Brush Tool use the pixels around the edge of the selection to pick the patch for repairing the selected area.
Step 3: Click on the area you want to fix (Fig. 8.4a and B).


The Clone Stamp Tool lets you duplicate the parts of an image by setting a sampling point in the image to be cloned. The cloned image can be drawn over another image or part of the same image.
The steps to use the Clone Stamp Tool are:
Step 1: Choose the Clone Stamp Tool.
Step 2: Click the appropriate settings in the Options bar (Fig. 8.5). These settings may include choosing a Brush Size Opacity value or setting the Aligned checkbox.

Step 3: Hold down the Alt key. The cursor shape changes to a target symbol. Click on the image to be cloned to set the sampling point.
Step 4: Click and drag where you want the cloned image to appear. When you draw, a plus sign (+) appears on the original image while a corresponding circle appears on the cloned image (Fig. 8.6a and b).


A pattern is usually a design made up of an image that is repeated or tiled. The Pattern Stamp Tool lets you fill an area with a selected pattern. Photoshop comes with a variety of preset patterns. You can select a preset pattern from the Photoshop library or create your own pattern.
The steps to use the Pattern Stamp Tool are:
Step 1: Select the Pattern Stamp Tool.
Step 2: Set appropriate options such as Brush Size, Mode, Opacity and Flow for the Pattern Stamp Tool in the Options bar (Fig. 8.7).
Step 3: Select a pattern from the Pattern Picker in the Options bar.

Step 4: Place the mouse pointer inside the area where you want to apply the pattern and drag the mouse. The area of the image across which you drag the mouse gets filled with the pattern (Fig. 8.8).


These tools let you change the appearance or the focus of selected portions of the image.
The Blur Tool softens the selected portions of an image giving it a blurred effect. This tool is useful in situations when you want to moderate or soften the focus of some areas of an image.
The Sharpen Tool is the opposite of the Blur Tool. This tool lets you improve the clarity of an image by sharpening the edges of selected portions of an image.
The Smudge Tool gives an effect of spreading the paint across the image as if you have dragged your finger through wet paint. This tool picks up the colour from where the stroke begins and pushes it in the direction you drag your mouse.

The steps to use the Blur, Sharpen and Smudge tools are:
Step 1: Select the Blur Tool, the Sharpen Tool or the Smudge Tool from the Tools panel.
Step 2: Set the Brush Size and Blending Mode for the tool in the Options bar.
Step 3: Drag the mouse pointer over the portion of the image you want to blur, sharpen or smudge (Fig. 8.10a and b, Fig. 8.1 la and b).


The Dodge Tool is used to lighten the areas of an image whereas the Burn Tool is used to darken the areas of an image.
The steps to use the Dodge tool or the Burn Tool are:
Step 1: Select the Dodge Tool or the Burn Tool.
Step 2: In the Options bar, set the appropriate Brush Size and select an appropriate Range option and the Exposure Level.
Step 3: Drag the mouse pointer over the area of the image you want to lighten or darken (Fig. 8.12a, b and c).

The Type Tools are used for inserting text in Photoshop. You can format the text in many ways such as changing its font family , size, style, colour, alignment, horizontal or vertical orientation, indentation, line spacing and much more. You can also warp the shape of the text in a number of interesting ways such as that of a wave, a flag or an arc.
Note: When you insert text in Photoshop, it is created on a separate layer called the Type Layer. You will learn more about layers later in this chapter.

The Type Tools available in the Tools panel that we will discuss in this chapter are:

• Horizontal Type Tool inserts text in the horizontal direction.
• Vertical Type Tool inserts text in the vertical direction.

The steps to use the Type Tool are:
Step 1: Open the image.
Step 2: Select the Horizontal Type Tool or the Vertical Type Tool.
Step 3: Set the appropriate options such as font family, size, style, alignment and text colour for the Type Tool in the Options bar (Fig. 8.14 and Fig. 8.15).

Step 4: Click to set the insertion point anywhere on the image.
Step 5: Enter the desired text.
Step 6: Accept changes to the text by clicking the Commit button or cancel the operation by pressing the Cancel button in the Options bar.

Warping Text
The steps to be followed for warping the text are:
Step 1: Place the cursor anywhere in the already written text.
Step 2: Select the Type tool.
Step 3: Click the Create warped text %, button in the Options bar. This displays the Warp Text dialog box (Fig. 8.16).
Step 4: Choose a warp style from the Style drop-down list.
Step 5: Select the orientation of the warp style—Horizontal or Vertical.
Step 6: If desired, specify values for additional options given in the Warp Text dialog box.
Step 7: Click OK to apply the warp style.

The Eraser Tool erases pixels as you drag it across an image. Pixels are erased to transparency or to the background colour if the layer is locked. There are three variants of this tool—Eraser Tool, Background Eraser Tool and Magic Eraser Tool (Fig. 8.18).

The Background Eraser Tool allows you to erase the background colour from an image or a layer. You will learn more about layers later in this chapter. The Background Eraser Tool picks up the sample colour when you click on the image and erases this colour as you drag the mouse (Fig. 8.19).

On the other hand, the Magic Eraser Tool erases all areas that share similar coloured pixels. When using this tool, click on the area containing the colour to be removed from the image. This erases all the coloured pixels within a set tolerance. You can associate the functionality associated with Magic Eraser Tool to using the Magic Wand Tool and then pressing Delete.

The steps to use the Eraser Tools are:
Step 1: Select the Eraser Tool, the Background Eraser Tool or the Magic Eraser Tool.
Step 2: Set the appropriate options for the eraser tools in the Options bar.
Step 3: Drag over the area you want to erase when using the Eraser or the Background Eraser Tool.
When using the Magic Eraser Tool, click on the part of the image you want to erase (Fig. 8.20).

Practice Zone
Which Photoshop tool will you use to

1. duplicate a part of an image by setting the sampling point in the image?
2. quickly remove blemishes and other marks in photos without setting the sampling point?
3. remove all areas that share similar pixels in an image?
4. darken certain areas of an image?
5. give an effect of spreading paint across the image?
6. moderate or soften the focus of some areas of an image?

Scan any of your old photographs. Make use of various Retouching Tools to   remove any scratches, marks and so on, in your photographs to give it a new and fresh look.

LAYERS
Layers can be thought of as transparent sheets mounted on the top of each other.
Layers let you work on an individual part or an element of an image without affecting the other parts or elements. You can change the composition of an image by changing the order and properties of layers. Elements placed on higher layers are displayed above the elements placed on lower layers.
Look at the graphic in Figure 8.21. To you, it may look a single, flat graphic but it is actually a combination of various elements placed on different layers. In the given graphic, the lady, flag, text and background are all placed on different layers (Fig. 8.22).

When you open a new image file with a white or a coloured background, the bottom-most image in the Layers panel is called Background. An image can have only one background. You cannot change the order of the background layer. You can add more layers, delete layers, show/hide layers, lock layers and use different layer styles to add sophisticated effects to your image.
Let us learn more about working with layers.

Working with Layers
Let us now learn about adding new layers, deleting layers, renaming layers, hiding and showing layers, changing the order of layers and layer effects in this section.

Adding a new layer
You can add a new layer by using any one of the following methods.
Click the New Layer button Ü in the Layers panel.
OR
Choose Layer → New → Layer.
A new layer with the name Layerl gets inserted above the selected layer.

Renaming a layer
You can rename a layer by double-clicking on the layer name in the Layers panel and typing a new name.

Deleting a layer
You can delete one or more layers by using any one of the following methods.
Select the layer and click the Delete Layer  button in the Layers panel.
OR
Choose Layer ? Delete ? Layer.
OR
Drag the Layer to the Delete Layer button.

Showing and hiding layers
To hide the layer contents, click the Eye icon next to a layer. Click in the Eye icon again to display the contents of the layer again.

Changing the order of layers
The elements that are placed on the higher layers are displayed above the elements placed on the lower layers. To change the placement of elements in an image, you can rearrange the layers containing them in the Layers panel. To change the order of layers, drag the layer to an appropriate position in the Layers panel.

Layer effects
Photoshop offers various layer effects that allows you to enhance the look of the contents of a layer. Some of these effects include shadow, glow, bevel, emboss and overlay.

The steps to apply the layer effects are:
Step 1: Select a layer in the Layers panel (Fig. 8.23).
Step 2: Click the Layer Styles button at the bottom of the Layers panel and choose an effect from the list, or Choose Layer ? Layer Style.
Step 3: The Layer Style dialog box appears (Fig. 8.24). Choose the desired effect by clicking the corresponding check boxes on. the left side of the dialog box.
Step 4: Set appropriate options for the selected effect on the right side of the dialog box.
Step 5: Click OK to apply the effect.

When you apply Layer effects, an ‘fx’ icon appears to the right of the layer name in the Layers panel. You can click on this icon to display the list of the effects applied on the layer (Fig. 8.25 and 8.26).

Create a beautiful scenery/greeting card/collage by placing various elements of an image on different layers. Apply layer effect to various elements of the | image. Also, make use of Type Tool to provide appropriate caption to your i
scenery/greeting card/collage.

Practice Zone
State whether the following statements are True or False.

1. Layers let you work on an individual part of an image without affecting others.
2. You cannot change the stacking order of layers.
3. When you insert text in Photoshop, it is created on a separate layer called the Type Layer.
4. Elements placed on higher layers are displayed below the elements placed on lower layers.
5. You cannot apply effects on layers.
6. An image can have only one background.

FILTERS
Filters let you change the appearance of an image by adding special effects to it. Filters are available under the Filter menu. Photoshop offers various categories of Filters. For example, you can use the Stylize filters to give a painted effect to your images, the Render filters to create 3D shapes, reflections in an image and so on.

Applying Filters
You can apply a filter to an entire layer, or a Selected portion of a layer. The steps to be followed are:
Step 1: Select the entire layer or a particular portion of a layer.
Step 2: Choose the desired filter from the Filter menu (Fig. 8.27).

Step 3: Some filters have a dialog box associated with them. If the dialog box appears, set the desired options in the dialog box to apply the filter. If no dialog box appears, the selected filter is applied directly to the image (Fig. 8.28 and Fig. 8.29).

Filter Gallery
Filter Gallery offers a convenient way of applying multiple filters on the image or applying individual filters more than once on an image.
To apply a filter or multiple filters on an image using the Filter Gallery, follow the given steps.
Step 1: Select the entire image layer or a particular portion of a layer to which the filter needs to be applied.
Step 2: Choose Filter ? Filter Gallery (Fig. 8.30). The Filter Gallery dialog box gets displayed.
Step 3: The Filter Gallery dialog box arranges filters by category. Click the inverted triangle next to the filter category to display the list of filters. Choose a filter name to add the first filter.

Step 4: Choose the desired settings for the selected filter. The applied filter gets added to the list at the lower-right corner of the Filter Gallery dialog box (Fig. 8.31).
Step 5: To apply additional filters to the image, click the New Effect Layer icon. Choose another filter to apply. Repeat this procedure to add more filters.

Step 6: To remove the already applied filters, select a filter in the applied filter list and click the Delete icon.
Step 7: If you are satisfied with the current image settings, click on OK.

CBSE Class 9 Maths Lab Manual – Areas of Two Triangles on the Same Base and between the Same Parallels

Objective
To show that the triangles on the same base and between the same parallel lines are equal in area experimentally.

Prerequisite Knowledge

1. Familiarity with triangles.
2. Formula for area of triangle = \(\frac{ 1 }{ 2 }\) x base x height.
3. Shortest distance between the two parallel lines.

Materials Required
Glazed papers, a pair of scissors, pencil, gluestick, white sheet.

Procedure

1. Draw any triangle on a glazed paper and name it as ABC.
2. Cut the triangle and paste it on the white sheet as shown in fig.(i).
   
3. Cut another triangle EGH such that EH = BC [fig .(ii)]
   
4. Draw a line l at point A such that l is parallel to BC as shown in fig.(iii).
5. Draw any triangle KBC with the base BC and its vertex K lying on the line l as shown in fig (iii).
6. Paste ∆EGH on ∆ABC such that EH lies on BC and G does not lie on line l as shown in fig (iii).
   

Observation
ar(∆ABC) = \(\frac{ 1 }{ 2 }\) x base x height
= \(\frac{ 1 }{ 2 }\) x BC x (⊥distance between || lines l and BC)
= \(\frac{ 1 }{ 2 }\) x BC x AM
ar(∆BKC) = \(\frac{ 1 }{ 2 }\) x BC x (⊥distance between || lines l and BC)
= \(\frac{ 1 }{ 2 }\) x BC x KL
= \(\frac{ 1 }{ 2 }\) x BC x AM (⊥distance between || lines is always same), (KL = AM)
∴ ar(∆ABC) = ar(∆BKC)
ar(∆EGH) = \(\frac{ 1 }{ 2 }\) x base x height
= \(\frac{ 1 }{ 2 }\) x BC x (⊥distance from G to BC)
= \(\frac{ 1 }{ 2 }\) x BC x GN
But, AM ≠ GN
∴ ar(∆ABC) ≠ ar(∆EGH)

Result
We have verified that two triangles on the same base and between the same parallel lines are equal in area.

Learning Outcome
We learnt that areas of two or more triangles are same if they lie on the same base and between the same parallel lines. Triangles having same base but different perpendicular heights are not same and their areas are also not equal.

Activity Time
Students can verify this theorem by graphical and counting method.
[Hint: Draw two triangles on the same base and between the same height and then count the squares covered by two triangles on the graph paper].

Viva Voce

Question 1.
Two triangles are on the same base and same height, area of one of the triangle is 4 cm². What will be the area of second triangle ?
Answer:
4 cm²

Question 2.
In a triangle, a median divides the triangle in two parts. What will be the area of two triangles, so formed ?
Answer:
Area of two triangles will be same.

Question 3.
If two triangles are having same areas then the triangles will be congruent ?
Answer:
Not necessary.

Question 4.
If two triangles are having same base 4 cm and their area is 12 cm2 and lying between the same parallel lines, what will be the height?
Answer:
6 cm.

Question 5.
Parallelograms on the same base and having equal areas lie between the same parallels. Is the converse true ?
Answer:
Yes, the converse is true.

Question 6.
If a triangle and a parallelogram are on the same base and between the same parallels, then what will be area of triangle ?
Answer:
Area of triangle is equal to half the area of parallelogram.

Question 7.
In the above question, area of parallelogram is 12 cm², what will be the area of the triangle ?
Answer:
6 cm²

Question 8.
If a triangle and a parallelogram are on the same base and not lie between same parallel lines, then will they have same altitudes ?
Answer:
No, they will not have same altitudes.

Question 9.
If two triangles are on same base and having same areas. What can you say about their heights.
Answer:
Their heights will be same.

Multiple Choice Questions

Question 1.
Triangles ABC and DBC are on the same base BC and with vertices A and D on opposite sides of BC such that ar (∆ABC) = ar (∆DBC). What is the relation between their altitudes ?
(i) equal
(ii) not equal
(iii) altitude of ∆ABC = altitude of ∆BDC
(iv) none of these

Question 2.
D and E are points on sides AB and AC respectively of ∆ABC, such that ar(∆DBC) = ar(∆EBC). Are lines DE and BC parallel to each other ?
(i) yes
(ii) no
(iii) DE = BC
(iv) none of these

Question 3.
In ∆ABC, AB = 8 cm and altitude corresponding to AB is 5cm. In ∆DEF, EF = 10 cm. Find the altitude corresponding to side EF, if ar (∆ABC) = ar(∆DEF):
(i) 8 cm
(ii) 5 cm
(in) 4 cm
(iv) none of these

Question 4.
The area of rectangle ABCD is 50 sq. cm. If P be any point on AB, find area of ∆PCD :
(i) 25 sq.cm
(ii) 100 sq.cm
(iii) 50 sq. cm
(iv) none of these

Question 5.
Find area of triangle whose base is (x – 3) and height is (x + 4) and its area is x²/2:
(i) 72 cm²
(ii) 12 cm²
(iii) 144 cm²
(iv) none of these

Question 6.
In triangle ABC, O is the mid-point on its median AD. If area of ∆ABD is 12 cm². Find area of ∆ABO:
(i) 12 cm²
(ii) 24 cm²
(iii) 6 cm²
(iv) none of these

Question 7.
In ∆ABC, D, E and F are mid-points of the sides BC, CA, AB respectively. If area of ∆ABC is 144 cm². What will be the area of triangle DEF ?
(i) 36 cm²
(ii) 12 cm²
(iii) 72 cm²
(iv) none of these

Question 8.
In ∆PQR, M, N, P are mid-points of the sides PQ, QR, RP respectively. If area of ∆PQR is 162 cm², then what will be the area of parallelogram PNQM ?
(i) 81 cm²
(ii) 41 cm²
(iii) 54 cm²
(iv) none of these

Question 9.
ABDE and BCDE are two parallelograms on the same base ED. AB = BC = DE. If ar(∆BDE) = 75 cm². What will be area of ACDE ?

(i) 75 cm²
(ii) 225 cm²
(iii) 3 cm²
(iv) none of these

Question 10.
AD is a median of ∆ABC. If ar(∆ABD) = x cm² and ar(∆ABC) = y cm². Find the relation between x and y:
(i) x – 2y
(ii) y – 2x
(iii) y – x
(iv) none of these

Answers

1. (i)
2. (i)
3. (iii)
4. (i)
5. (i)
6. (iii)
7. (i)
8. (i)
9. (ii)
10. (ii)

Math Lab ManualMath Labs with ActivityMath LabsScience LabsScience Practical Skills

CBSE Class 9 Science Practical Skills – Density of Solid

Basic Building Concepts
Density
It is the physical property of a matter that describes how the individual particles of the substance are closely packed together. In other words, it describes the degree of compactness of a substance.
In qualitative manner, the density of a substance is defined as its mass per unit volume, i.e.,
Density(ρ) = \(\frac { Mass(M) }{ Volume(V) }\)
The amount of matter contained in the body is called mass. The mass is measured commonly in grams (g) and its SI unit is kilogram (kg).
The space occupied by the quantity of matter is called volume of the object. It is measured in cubic centimetres (cm³) and its SI unit is m³.
Therefore, unit of density is g/cm³ or kg/m³
1 kg m^-3 = 10^-3 gcm^-3

You can also Download Class 9 Science Notes PDF to help you to revise complete Syllabus and score more marks in your examinations.

Density of Some Common Substances
The density of a given substance, under specified condition, is always the same. Therefore, it is a characteristic property. It is different for different substances as shown in the following table:

Substances	Densities
	g cm-3	kg m-3
Air	0.0013	1.30
Ice	0.92	920
Water	1.00	1000
Common Salt (NaCl)	2.16	2160
Aluminium	2.70	2700
Iron	7.80	7800
Silver	10.50	10500
Gold	19.30	19300

From the table, it is clear that the different substances have different densities. Thus density measurements provide a useful tool for identifying substances either molecules of a compound or atoms of an element.
The factor that can affect the density of a material is temperature. When the temperature of a substance increases, its density decreases.
Applications

• Categorise the substance.
• Identify the different materials.
• For building ships and making hot air balloons.
• Determine the purity of a substance.

Examples

• Ice floats on water.
• Oil floats on the surface of water.
• Stone sinks in liquid (water).

Relative Density
When density of a substance is compared with the density of water, then it is called relative density. Thus relative density of a substance is the ratio of its density to that of water at 4°C having the same volume as that of the substance.
Relative Density(R.D.) = \(\frac { Density\quad of\quad Substance({ \rho  }_{ s }) }{ Density\quad of\quad Water({ \rho  }_{ w })\quad at\quad { 4 }^{ 0 }C }\)
or
R.D. = \(\frac { { \rho  }_{ s } }{ { \rho  }_{ w } }\)
Since the relative density is expressed in terms of ratio, it has no unit.
If the relative density of a substance is more than 1, the substance would sink in water. For example, relative density of iron is 2.70, so it sinks in water.
If R.D. < 1, the substance or object floats on the surface of water. For example, ice block.

Spring Balance
It is simply a spring whose one end is attached to a rigid support and other free end with a hook attached to another object.
Working Principle of Spring Balance
It works on the principle of elasticity. Applied force to stretch a spring is directly proportional to the change in length from its mean position. Therefore, the scale marking on the spring scale are equally spaced. Mathematically,
F ∝ x
or F = -kx
where F is the force exerted by a spring, and x is the displacement of the end of a spring from its equilibrium position. The proportionality constant ‘k’ is called ‘spring constant’. More the spring constant, harder the spring to stretch out.
Negative sign indicates that applied force and spring stretched distance both are in opposite directions as shown below.

On hanging the object from the hook, spring will stretch. Let the change in length of spring be x. The mass of the object is pulled down by force of gravity (mg) and pulled up by the spring force (F). These forces balance each other, i.e., F = mg. Thus with the help of a spring, we can measure the weight of the body not the mass of the body. If the scale of spring balance is calibrated in gram, then the weight of solid is measured in gram-weight. Weight of the body in gram-weight is numerically equal to the mass of the solid.

Uses

• Spring balance or spring scale is used in physics as a basic accelerometer.
• For weighing heavy loads in industry.
• To measure the weight of materials carried on a conveyor belt.

Aim
To determine the density of a solid (denser than water) by using a spring balance and a measuring cylinder.

Apparatus Required
A metallic object (any shape), iron stand, a spring balance, a measuring cylinder (preferably 0-250mL)

Theory
Mass per unit volume of a substance is called the density of a given substance.
Let M be the mass of a given substance/object and V be its volume. Its density ρ is given by
ρ = \(\frac { M }{ V } =\frac { Mass\quad of\quad Object }{ Volume\quad of\quad Object }\)
Its S.I. unit is kg m^-3.
Let the weight of object measured by the spring balance in air = W g-wt.
Initial volume of water in measuring cylinder = V₁ mL.
Final volume of water in measuring cylinder when object is fully immersed in water = V₂ mL.
Volume of object = Volume of displaced water = (V₂ – V₁) mL
Therefore, density of object (ρ) = \(\frac { W }{ { V }_{ 2 }-{ V }_{ 1 } }\) g cm^-3

Procedure

1. Hang the spring balance vertically with the help of iron stand as shown in Fig. 2.2.
2. Find its least count by using the given formula:
   Least Count = \(\frac { Rangeofgiven\quad spring\quad balance }{ Total\quad number\quad ofdivisions }\)
3. Check the zero error (if any) and record it with proper sign.
   This is the reading of spring balance when no weight is suspended from its lower hook.
   
   Measurement of weight of a given metallic object:
4. Hang the metallic object with the lower hook of the spring balance as shown in Fig. 2.3.
5. Take the reading of spring balance when the metallic object becomes static.
6. Obtain the true weight of the given metallic object by subtracting the zero error (if any) from the observe weight.
7. Repeat the experiment thrice and find its mean weight.
   Measurement of the volume of a given metallic object:
8. Pour some water into the measuring cylinder and record the initial level of water (lower position of meniscus) as shown in Fig. 2.4. Let the initial volume be V₁ (mL).
9. Remove the metallic object from the spring balance and tie it by a thin strong thread and immerse it fully in the water in measuring cylinder.
10. Note down the new position of meniscus V₂ (mL) in the measuring cylinder as shown in Fig. 2.5. The level of water rises up because the immersed object displaces water from its initial level.
11. Obtain the volume of the immersed metallic object by subtracting the two position of meniscus (water level) i.e. V₂ – V₁
12. Repeat the experiment thrice and find its mean volume.
    

Observations
Least count of spring balance: ………… g wt.
Zero error of the spring balance: …………. g wt.
Least count of measuring cylinder: ……….mL
Table: Measurement of weight of a given metallic object.

S.No.	Reading of spring balance		Weight of metallic object
	(without object) W1 (g wt.)	(with object) W2 (g wt.)	Weight of object observed W2 – W1 (g wt.)	True weight of object W = (W2 – W1) – (Zero error) (g wt.)
1.				W’1 =
2.				W’2 =
3.				W’3 =

Mean weight of given metallic object = \(\frac { { W }_{ 1 }^{ ‘ }+{ W }_{ 2 }^{ ‘ }+{ W }_{ 3 }^{ ‘ } }{ 3 }\) = ………..g wt.
Mass of the given metallic object by spring balance, (M) = ………….. g.
Table: Measurement of volume of a given metallic object

S.No.	Initial position of meniscus (Without metallic object) V1 (mL)	Final position of meniscus (Metallic object immersed) V2 (mL)	Volume of object V = V2 – V1 (mL)
1.			V’1 =
2.			V’2 =
3.			V’3 =

 Mean volume V = \(\frac { { V }_{ 1 }^{ ‘ }+{ V }_{ 2 }^{ ‘ }+{ V }_{ 3 }^{ ‘ } }{ 3 }\) = ………….mL

Calculations
True mass of given object = ………… g
Volume of given object = …………..mL
Density of a given metallic object = \(\frac { Mass\quad of\quad Object }{ Volume\quad of\quad Object } =\frac { M }{ V }\) g/mL = ……….g/mL = ………… kg m^-3 ( 1000 kg m^-3 = 1 gmL^-1)

Result
The density of the given solid (heavier than water) = ……… kg m^-3.

Precautions

1. Spring balance should be sensitive, stable and error free.
2. The horizontal pointer should move freely along the scale of spring balance.
3. Spring balance must be suspended vertically from fixed support of iron stand.
4. Reading should be taken only when oscillation of hanging object dies completely.
5. Eye should be kept in line (exactly horizontal) while taking the reading of spring balance as well as measuring cylinder as shown in figs. 2.6 and 2.7.
6. Solid object should be dried completely before measuring mass in air and when allowed to immersed in water.
7. While measuring the volume of object, the object should not touch sides and bottom of a measuring cylinder.
8. The water of the measuring cylinder should not fall out during immersing of solid object.
   

Source of Error

1. Least count of spring balance may be higher.
2. Spring of spring balance may be permanently stretched.
3. Solid object may not be completely dried.
4. The eye may not be in the proper level of meniscus while measuring the volume of solid object.

Interactive Session

Question 1.
What is the aim of your object?
Answer:
To determine the density of a given solid (denser than water) by using spring balance and measuring cylinder.

Question 2.
What is the unit of density?
Answer:
g cm^-3 or kg m^-3.

Question 3.
What is the relation between mL and cm³?
Answer:
1 mL = 1 cm³.

Question 4.
Is there any effect of temperature on the density?
Answer:
Yes, density of a substance decreases with the rise in temperature.

Question 5.
Why?
Answer:
Due to rise in temperature, volume of the body increases and hence density decreases.

Question 6.
What is the density of water at 4°C?
Answer:
It is 10³ kg/m³ or 1 gm/cm³.

Question 7.
What is the difference between mass and weight?
Answer:
Mass is a measure of the quantity of matter, which is constant all over the universe. Weight is proportional to the mass but depends on the gravity of the planet.

Question 8.
What is weight?
Answer:
Weight is the force exerted on a body by gravitational attraction of the planet (earth).

Question 9.
Convert 500 g mass into unit of force.
Answer:
Unit of force is newton (N)
F = mg = \(\frac { 500\quad kg }{ 1000 } \times 9.8\) m/s² = 4.9 kg ms^-2 = 4.9 N

Question 10.
Name the device which measures the mass and weight.
Answer:
Mass is measured by physical balance. Weight is measured by spring balance.

Question 11.
What is the working principle of spring balance?
Answer:
The extension in the length of spring when the body is suspended from its free end, is directly proportional to the weight of the body.

Question 12.
You stated that weight was measured by spring balance, then how can you deduce mass from weight?
Answer:
The weight of the body in gram-weight is numerically equal to the mass of solid,
i. e., 100 gwt. = 100 gf = 100 g. or 100 kgwt. = 100 kg f = 100 kg.

Question 13.
How can we minimise the error in the measurement of volume of water in the measuring cylinder?
Answer:
We can use the measuring cylinder having a scale of less least count.

Question 14.
What change in volume of water observe when water is heated uniformly from 0°C to 100°C?
Answer:
The volume of water decreases upto 4°C and then further increases.

Question 15.
Which water has the lesser density River water or Sea water?
Answer:
River water.

NCERT Lab Manual Questions

Question 1.
Can you determine the density of a porous solid by using a spring balance and a measuring cylinder? Give reasons in support of your answer.
Answer:
No, we cannot determine the density of a porous solid by using a spring balance and a measuring cylinder because

1. the porous solid have a void space in the form of pores in it.
2. It will absorb some water.
3. absorption of water by the porous solid may affect the
   • change in its weight and
   • volume of water displaced by it.

Question 2.
How does the presence of an air bubble in the liquid taken in the measuring cylinder affect the volume of the solid?
Answer:
The presence of air bubble inside the water taken in the measuring cylinder increases the volume of water in the cylinder. This may affect the apparent change in volume of the solid.

Question 3.
Density of a sealing wax is 1.8 g/cm³, express it in kg/m³.
Answer:
Density of a sealing wax is 1.8 g/cm³
1.8 g/cm³ = \(\frac { { 1.8 }\times { 10 }^{ -3 } }{ ({ 10 }^{ -2 })^{ 3 } }\) kg/m3 = 1.8 x 10³ kg/m³

Question 4.
A metal cylinder is melted and the whole mass is cast in the shape of a cube. What happens to its density? Give reasons.
Answer:
In both the cases, (i) mass and (ii) volume of water displaced by the metallic cylinder and cube remain same. So mass per unit volume does not change. Hence the density of a cube will be equal to the density of the cylinder.

Question 5.
At which temperature is the density of water maximum?
Answer:
Density of water is maximum at 4°C because water when cooled contracts upto 4°C and it expands when cooled further below 4°C. (The density of water at 4°C = 1000 kg/m³)

Practical Based Questions

Multiple Choice Questions/VSA (1 Mark)

Question 1.
The density of which of the following cannot be measured accurately using a spring balance and a measuring cylinder? [CBSE 2010]
(a) A ball filled with a liquid having a leakage
(b) A block of ice at 0 °C
(c) A small porous solid
(d) All of these

Question 2.
You are given a sphere of radius 2 cm. If you are asked to select a best suited spring balance to determine its weight, then out of the following which one would you prefer? The sphere is made of an alloy of density 7 x 10³ kg m^-3. [CBSE 2011, 2010, NCT 2007]
(а) Range 0 – 1000 gwt, Least count 5 g wt
(b) Range 0 – 500 gwt, Least count 2.5 gwt
(c) Range 0 – 250 gwt, Least count 2.5 gwt
(d) Range 0 – 100 gwt, Least count 1 gwt

Question 3.
The water level in a measuring cylinder, before and after immersing a metal cube in it, is shown in the figure. The volume of the metal cube is: [CBSE 2010]

(a) 24 cm³
(b) 22 cm³
(c) 20 cm³
(d) 18 cm³

Question 4.
Four measuring cylinders with least count 2.5 ml, 1.0 ml and 0.5 ml and 0.2 ml are available. Which one should be preferred for finding the density of a solid accurately? The one having least count:
[CBSE 2011, 10]
(a) 2.5 ml
(b) 1.0 ml
(c) 0.5 ml
(d) 0.2 ml

Question 5.
Three students A, B and C noted the water level reading in the measuring cylinder, as shown in figure. The correct way of taking reading is of: [CBSE 2010]

(a) A and C
(b) Only B
(c) Only C
(d) A and B

Question 6.
In a spring balance the space between 0 and 25 g marks is divided into 10 equal parts. The least count of spring balance is: [CBSE 2010]
(a) 2.5 g wt
(b) 25 g wt
(c) 0.25 g wt
(d) 15 g wt

Question 7.
The least count of the spring balance shown in the diagram is: [CBSE 2010]

(a) 5 g
(b) 2 g
(c) 1 g
(d) 0.5 g

Question 8.
In the following figure the zero error is: [CBSE 2010]

(a) 2 g wt
(b) -2 g wt
(c) 5 g wt
(d) -5 g wt

Question 9.
If we want to determine the volume of a solid by immersing it in water, the solid should be
[CBSE 2010]
(a) lighter than water.
(b) heavier than water.
(c) insoluble in water.
(d) heavier than water and insoluble

Question 10.
The correct way of reading the liquid level is shown in [CBSE 2012, 2011]

(a) Figure A
(b) Figure B
(c) Figure C
(d) Figure D

Question 11.
A given solid is weighed in air using a spring balance. It is then weighed by immersing it fully, in each of the three different vessels A, B and C as shown. The weight of solid would be [CBSE 2012]

(a) more in vessel C
(b) more in vessel B
(c) more in vessel A
(d) equal in all the three vessels.

Question 12.
The level of water in a measuring cylinder before and after a solid of 8 g mass is fully immersed into it as shown.

The density of the given solid is: [CBSE 2012]
(a) 4 g/cm³
(b) 2 g/cm³
(c) 3 g/cm³
(d) None of these

Question 13.
The least count of the spring balance and the measuring cylinder respectively are: [NCT 2007]

(a) 1 g wt; 1 ml
(b) 1 g wt; 2 ml
(c) 2 g wt; 1 ml
(d) 2 g wt; 2 ml

Question 14.
A student performing the experiment ‘To determine the density of solid (denser than water), by using spring balance and measuring cylinder’. During the experiment, he observed that a few air bubbles are sticking to the solid when immersed in water. The presence of air bubbles will lead to
(a) no change in density
(b) increase in density
(c) decrease in density
(d) none of the above

Question 15.
A spring balance reads 10 kg when a bucket of water is suspended from it. An iron piece having some mass is suspended by another string and immersed in the bucket with half of its volume. The reading of balance will
(a) decrease
(b) increase
(c) remain the same
(d) another spring balance needed

Question 16.
While determining the density of a copper piece using a spring balance and a measuring cylinder, seema carried out the following procedure:
(i) Noted the water level in the measuring cylinder without the copper piece.
(ii) Immersed copper piece in water.
(iii) Noted the water level after immersing copper in the measuring cylinder.
(iv) Removed the copper piece from the water and immediately weighted it using a spring balance.
The wrong step in the procedure is:
(a) (i)
(b) (ii)
(c) (iii)
(d) (iv)

Question 17.

Four measuring cylinders with different least counts are shown in figures A, B, C and D respectively. The most suitable cylinder for determining the volume of a cube of side 1 cm is
(a) A
(b) B
(c) C
(d) D

Question 18.
While determining the density of a solid, a student is provided with four different combinations.
Measuring cylinder

S. No.	Range	Least count
1.	0 – 100 ml	1 ml
2.	0 – 200 ml	5 ml
3.	0 – 100 ml	2 ml
4.	0 – 200 ml	2 ml

 Spring balance

S. No.	Range	Least count
1.	0 – 100 g wt	1 g wt
2.	0 – 200 g wt	5 g wt
3.	0 – 100 g wt	2 g wt
4.	0 – 200 g wt	2 g wt

The student should prefer to choose combination
(a) 1-1
(b) 2-2
(c) 3-3
(d) 4-4

Question 19.
A student notes down the observations in two spring balances and the measuring cylinder shown in the figure. From the given observations, the volume of the solid is

(a) 64 cc
(b) 36 cc
(c) 28 cc
(d) 100 cc

Answers

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

Short Answer Questions (2 Marks)

Question 1.
Define relative density of a substance. Relative density of silver is 10.8. The density of water is 1000 kgm^-3. What is the density of silver in SI units?
Answer:
Relative density is defined as the ratio of density of a substance to the density of water. Therefore,
Relative density = \(\frac { Density\quad ofa\quad substance }{ Density\quad of\quad water }\)
Density of silver = Relative density of silver x Density of water
= 10.8 x 1000 = 1.08 x 10⁴ kgm^-3.

Question 2.
Differentiate between density and relative density.
Answer:

Density	Relative density
1. It is equal to the mass per unit volume of a body.	1. It is the ratio of density of a body to the density of water.
2. Its unit is SI kgm-3.	2. It has no unit as it is the ratio of same quantity.

 Question 3.
Arpita was given a solid sphere of metal of mass 100 g. She immersed it in a measuring cylinder and found that the level of water was raised by 30 mL. Calculate the density of metal as measured by her.
Answer:
Mass of solid = 100 g
Volume of solid=30 mL
Density of solid = \(\frac { Mass\quad of\quad Solid }{ Volume\quad of\quad Solid } =\frac { M }{ V } =\frac { 100 }{ 30 }\) = 3.33 gmL^-1

Question 4.
In the experiment, to determine the density of a given solid (denser than water) by using a spring balance and a measuring cylinder, a student made the following observations.

• Mass of solid = 115 g
• Initial reading of water level in measuring cylinder = 45 mL
• Final reading of water level in measuring cylinder = 69 mL

On the basis of these observations, what should be the density of a given solid if the spring balance showed a reading of -5 g before suspending the solid?
Answer:
Corrected mass of the solid = 115 – (-5) = 120 g
Density of solid = \(\frac { Mass\quad of\quad Solid }{ Volume\quad of\quad Solid } =\frac { M }{ V } =\frac { 120\quad g }{ \left( 69-45 \right) mL } =\frac { 120\quad g }{ 24\quad mL }\) =5 gmL^-1

Question 5.
The density of aluminium is 2700 kgm^-3. What does it mean? Calculate the density of aluminium 1 in CGS system.
Answer:
It means that 1 m³ volume of aluminium has a mass of 2700 kg.
Density of aluminium in CGS system
= \(\frac { 2700\times 1000 }{ 100\times 100\times 100 }\)
= 2700 x 10^-3
= 2.7 g cm^-3

Science Practical SkillsScience LabsMath Lab ManualMath Labs with ActivityMath Labs

CBSE Class 9 Maths Lab Manual – Quadrilateral Formed by Joining Mid-points of Sides of a Quadrilateral

Objective
To show that the quadrilateral formed by joining the mid-points of the adjacent sides of a quadrilateral is a parallelogram by paper folding.

Prerequisite Knowledge

1. Concept of finding mid-point of a line segment by performing paper folding activity.
2. Properties of a parallelogram.

Materials Required
Glazed papers, pencil, a pair of scissors, gluestick and tracing paper.

Procedure

1. Take any coloured glazed paper.
2. Draw a quadrilateral of any dimensions on glazed paper and name it as ABCD.
3. Cut that quadrilateral from the glazed paper.
4. Now, find the mid-point of each side AB, BC, CD, DA by paper folding and name them E, F, G, H respectively as shown infig. (i).
   
5. Now, fold the figure along EF, GF, GH and EH. Press it and then unfold it as shown in fig. (ii).
   
6. We will get creases along EF, GF, GH, HE.
7. Make a replica (true copy) of EFGH (say PQRS) by using a tracing paper [fig.(iii)].
   
8. Cut the quadrilateral PQRS along any diagonal (say RP) [fig.(iv)].
   
9. We will get two triangles ∆PSR and ∆PQR.
10. Now, overlap these two triangles. Two triangles coincide with each other [fig.(v)] such that side PS overlaps with QR and PQ with SR.
    

Observation
We observe that two triangles coincide with each other which means two triangles are congruent to each other. In a quadrilateral, two triangles cover each other completelv along any diagonal, then the quadrilateral will be a parallelogram.
∴ ∆PQR = ∆PSR
i.e., ar (∆PQR) = ar(∆PSR)
∴ PQRS is a parallelogram.

Result
As the replica of ∆PQR exactly covers the replica of ∆PSR
∴ PQ = RS, QR=SP
∴ PQRS is a parallelogram.

Learning Outcome
We have verified by paper folding that the quadrilateral formed by joining the mid-points of adjacent sides of a quadrilateral will be a parallelogram. We also learnt that a diagonal always divides the parallelogram into two triangles of equal areas.

Activity Time
What type of figures do you obtain?

• If you join mid-points of the sides of a rectangle (Do it by paper folding).
• If you join the mid-points of thesidesof a square (Do it by paper folding).

Viva Voce

Question 1.
What do you mean by a quadrilateral ?
Answer:
A quadrilateral is a plane closed figure bounded by four line segments.

Question 2.
What are two main properties of a quadrilateral ?
Answer:

• Sum of four angles is 360°.
• It has 4 sides.

Question 3.
Is a parallelogram a quadrilateral ?
Answer:
Yes

Question 4.
Write two main properties of a parallelogram.
Answer:

• Diagonals bisect each other.
• Opposite sides are equal.

Question 5.
In a parallelogram, if one angle is 90°, then what type of parallelogram you will get ?
Answer:
Rectangle.

Question 6.
Do you know any difference between a parallelogram and a trapezium ?
Answer:
In a parallelogram, two pairs of opposite sides are parallel. In a trapezium, one pair of opposite sides is parallel.

Question 7.
What is the area of a parallelogram ?
Answer:
Base x corresponding altitude.

Question 8.
If base and altitude of a parallelogram are same, then what will be area of parallelogram ?
Answer:
Base x altitude.

Question 9.
If base and altitude of a parallelogram are same, then what type of parallelogram will be obtained ?
Answer:
Square.

Question 10.
What do you mean by a parallelogram ?
Answer:
A parallelogram is a quadrilateral in which opposite sides are equal and parallel.

Question 11.
Write the name of different kinds of parallelograms.
Answer:
Rectangle, square and rhombus.

Question 12.
If you join the mid-points of consecutive sides of a quadrilateral, what shape will you obtain ?
Answer:
Parallelogram.

Question 13.
Which theorem is used in this activity ?
Answer:
Mid-point theorem.

Question 14.
If you join the mid-points of consecutive sides of a rectangle, what figure will you obtain ?
Answer:
Rhombus.

Question 15.
If you join the mid-points of consecutive sides of a rhombus, what figure will you obtain ?
Answer:
Rectangle.

Multiple Choice Questions

Question 1.
Name the quadrilateral formed by joining the mid¬points of the consecutive sides of a square:
(i) rectangle
(ii) square
(iii) rhombus
(iv) none of these

Question 2.
The four triangles formed by joining the mid-points of three sides of a triangle are:
(i) congruent
(ii) non-congruent
(iii) similar
(iv) none of these

Question 3.
In the given figure ABCD, if P, Q, R and S are the mid-points of sides AB, BC, CD and DA respectively, then:

(i) SR = \(\frac { 1 }{ 2 }\) AC
(ii) SR = AC
(iii) SR = \(\frac { 1 }{ 3 }\) AC
(iv) none of these

Question 4.
In ∆ABC, if E is the mid-point of AC, F lies on BC and EF // AB then:
(i) EF = \(\frac { 1 }{ 3 }\) AB
(ii) EF = \(\frac { 1 }{ 2 }\) AB
(iii) EF = AB
(iv) none of these

Question 5.
In a parallelogram, the figure formed by joining the mid-points of consecutive sides is :
(i) a rectangle
(ii) a rhombus
(iii) a square
(iv) none of these.

Question 6.
In a rhombus, diagonals bisect each other at an angle of:
(i) 45° and 135°
(ii) 60° and 120°
(iii) 90°
(iv) none of these

Question 7.
In a rectangle, diagonals are:
(i) equal
(ii) not equal
(iii) half of each other
(iv) none of these

Question 8.
The straight line joining the mid-points of the non¬parallel sides of a trapezium is parallel to:
(i) parallel sides
(ii) non-parallel sides
(iii) one non-parallel side
(iv) none of these

Question 9.
The triangle formed by joining the mid-points of the sides of a right triangle is :
(i) a right triangle
(ii) an obtuse-angled triangle
(iii) an isosceles triangle
(iv) none of these

Question 10.
The triangle formed by joing the mid-points of the sides of an isosceles triangle is:
(i) an equilateral triangle
(ii) an isosceles triangle
(iii) a right-angled triangle
(iv) none of these

Answers

1. (ii)
2. (i)
3. (i)
4. (ii)
5. (iv)
6. (iii)
7. (i)
8. (i)
9. (i)
10. (ii)

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Looking for an easy way to Learning of new elementary english grammar and composition for class 7 answers, Solutions. You have to learn basic English Grammar topics like Tenses Verbs, Nouns, etc… In this article, we will review the best English Grammer Topics and compare them against each other.

Possessive Exercises With Answers for Class 7 CBSE PDF

Possessives are used to indicate ownership. Possessive Nouns are usually formed by adding an apostrophe (‘) and s.
Examples:

• Pawan’s book/Kiran’s car/Grandma’s mirror

When a noun is plural and ends in s, we just add an apostrophe (‘) at the end to show possession.
The kids’ toys / My parents’ house / The teachers’ lounge

If two people own one thing, add the apostrophe and s only to the second person only.
Examples:

• Neena and Anil’s new house/Deepak and Jyoti’s wedding/Rahul and Rohit’s car

If two people own separate things, add the apostrophe and s for each person.
Examples:

• Suman’s and Babita’s books/Jiwan’s and Dilip’s pants/Bunty’s and Jiwan’s offices

Possessive Pronouns:
Examples:
in the sentence, “These books are mine, not yours”, the words “mine” and “yours” are possessive pronouns and stand for “my books” and “your books,” respectively.

Look at the following Examples:
Possessive Pronouns

• I like your drawing.
  Do you like mine.
• My flowers have withered.
  Yours are lovely
• Your photos are good.
  Mine are terrible.

The words mine, yours, his, hers, its, ours, theirs are possessive pronouns. They show who or what something belongs to.

Possessive Adjective:
Possessive adjectives – my, your, his, her, its, our, your, their – modify the noun following it in order to show possession.

Possessive Pronouns

• We have a dog his name is victor
• I like singing my mother sings with me.
• Namite is from sechi his husband is from Kolkata:
  

  Subject Pronouns		I	you	he	she	it	we	you	they
  Possessive	Adjectives	my	your	his	her	its	our	your	their
  	Pronouns	mine	yours	his	hers	its	ours	yours	theirs

Presentation:
Read the picture story.

Answer the following questions.

1. What did father bring for his family?
2. What did father bring for his sons, wife and daughter?
3. What was the most exciting thing?

A. Complete the blanks using the possessive adjectives.

1. Amit is from New Delhi and ___________ teacher is from Lucknow.
2. Maya is from Mumbai and ___________ doctor is from Chandigarh.
3. I am from Bihar and ___________ architect is from Rajasthan.
4. Maya and Kavita are Indian and ___________ friends are Brazilian.
5. Pierre and I are French and ___________ students are English.
6. Tilak and you are engineers and ___________ telephone number is 555-5678.
7. Anu and ___________ teacher are from Punjab.
8. Vijay is ___________ first name.

B. Form sentences using suitable possessive adjectives.
Examples:

• I/address/ II Baker Street
• My address is II Baker Street.

1. She/telephone number/888-0000
______________________
2. He/mechanic/Vijay Mathur
______________________
3. We/teacher/Sunita Rai.
______________________
4. They/zip code/55909
______________________
5. You/address/10 Violet Street
______________________
6. She/nickname/Mamta
______________________
7. I/number/ten
______________________
8. He/telephone/8822-2323/number
______________________
9. She/nickname/Vinita
______________________

C. Choose and circle the correct alternative.

1. Alok always types (his/hers) letters, but we never type (our/ours).
2. Kiran and Suman are waiting for (their/theirs) parents.
3. I know (my/mine) family very well. Do you know (yours/your)?
4. (Your/Yours) is an excellent car. How much did you pay for it?
5. She always shouts at (her/hers) children.
6. Children ask (theirs/their) parents difficult questions.
7. Give him (your/yours) address.

D. Write the correct possessive pronoun for each sentence.

1. I’ll do ___________ job, you do ___________
2. She can do ___________ homework alone. He can’t do ___________
3. We must wash ___________ hands before we eat.
4. The boys aren’t going to clean ___________ rooms today.
5. Dr. Mathur washes ___________ car every morning.

E. Choose the correct option to fill in the blanks.

1. Does ___________ bring ___________ books to the class?
a) he – him b) she – her c) her – she d) she – hers

2. Do you prefer listening to ___________ records or ___________?
a) your – yours b) my – him c) your – our d) your – mine

3. Lalit must talk to ___________ coordinator.
a) ours b) mine c) his d) him

4. Mrs. Khanna and ___________ children are waiting for ___________ answer.
a) his – our b) their – yours c) her – our d) her – ours

F. Read the text and choose the right word to complete the following paragraph.
Hi, I’m Ganesh and this is (1) ___________ sister Kiran. This is a photo of (2) ___________ mum and dad.

(3) ___________ teachers. My mum is 35 and (4) ___________ a maths teacher. (5) ___________. favourite place is California. My dad is 38 and (6) ___________ an English teacher.

(7) ___________ favourite place is Blackpool! (8) ___________ favourite people are Kiran and me, of course.

1. a) my – b) me
2. a) we – b) our
3. a) They’re – b) Their
4. a) she’s – b) he’s
5. a) Her – b) His
6. a) she’s – b) he’s
7. a) His – b) Her
8. a) They – b) Their

G. Fill in the blanks with the correct possessive adjective.

1. The children drink ___________ milk.
2. The woman said it was ___________ car.
3. You could see that the boy liked ___________ father very much.
4. We always complete ___________ homework.
5. I would like to go to ___________ cousin’s house next week.

H. Fill in the blanks with the correct possessive pronoun.

1. This is not her dress. Where’s ___________ ? (her dress)
2. They drank out of my glass yesterday, now I’m drinking out of ___________ (their glasses)
3. This piece of cake is ___________ (his piece)
4. These toys are ___________ (your toys)
5. These pictures are ___________ (Pawan and Maya’s picture)

I. Fill in the blanks with the pronouns from the box. One pronoun can be used more than once.
my – your – his – her – our – their

1. She’s really beautiful ___________ name is Suman.
2. He’s very intelligent ___________ name is Rohan.
3. They’re really smart. ___________ names are Mita and Gita.
4. ___________ name is Deepak.
5. ___________ names are Dipika and Gitika. We’re sisters.
6. ___________ brothers’ names are Deepak and Sandeep.
7. ___________ friend’s name is Pradip.

J. Fill in the blanks with his, her, your or their.

1. ___________ name is Monica.
2. ___________ name is Jatin.
3. What’s name? My ___________ name is Anu.
4. What’s ___________ nationality? They’re Brazilian.

K. Rewrite the following sentences using possessive pronouns/adjectives. The first one has been done for you.
1. Harshit’s book is in the classroom.
His book is in the classroom.

2. These watches belong to me.
______________________
3. Excuse me, does this mobile belong to you?
______________________
4. Those pens belong to Mayank and Chetna.
______________________
5. Meena’s shoes are in her bedroom.
______________________
6. The children’s pencils are on the table.
______________________
7. Manshu’s bag is in the living room.
______________________
8. Those trousers belong to Sahil.
______________________
9. Anita’s skirt is in the wardrobe.
______________________