Question
Coliform bacteria are mainly present in human faeces.
Drinking water should not contain more than 1 coliform per 100 mL.
The graph shows the amount of coliforms found in four water samples collected for a study.

Image
1. What can be concluded from the graph?
A. Sample 1 is safe for drinking.
B. Sample 3 is least contaminated with human faeces.
C. Sample 2 and sample 4 are collected from the same water source.
D. Sample 1 and sample 2 contain the same concentration of coliforms.
2. Bathing water should not contain more than 1000 coliforms per 100 mL.
Which water sample is safe for bathing?
A. Sample 1
B. Sample 2
C. Sample 3
D. Sample 4
3. The same study was repeated over a period of ive years.
Which questions can be answered by comparing the results of the study?
Circle ‘Yes’ or ‘No’ for the correct response.

Can this question be answered by the study?

Yes or No

Is the pollution in the water sources increasing over time?

Yes/No

Which water source is the most polluted?

Yes/No

What are the chemical wastes present in the water sources?

Yes/No

4. Industrial wastes entering rivers often make the river water acidic.
How can this lead to a decrease in the population of many aquatic organisms?
5. Which of these activities should be prohibited in water bodies to control water pollution?
A. Fishing
B. Swimming
C. Rowing boats
D. Washing Clothes
The table lists the number of species of plants and animals in four forests over a time period

Year - 1980

Year - 2000

Plants

Animals

Plants

Animals

Forest 1

780

205

705

180

Forest 2

1255

410

1240

400

Forest 3

1740

685

1080

395

Forest 4

685

210

650

205

6. Which forest was the most biodiverse in the year 2000?
A. Forest 1
B. Forest 2
C. Forest 3
D. Forest 4
7. Which forest had the greatest loss of biodiversity between 1980 and 2000?
A. Forest 1
B. Forest 2
C. Forest 3
D. Forest 4
8. Which of these areas has the greatest biodiversity?
A. Desert
B. Rainforest
C. Grassland
D. Mountain
9. Which of these is a bad effect of burning fossil fuels?
A. Depletion of ozone layer
B. Increase in global warming
C. Increase in atmospheric nitrogen
D. Decrease in atmospheric oxygen
10. Which of these is an effect of construction of dams?
Circle ‘Yes’ or ‘No’ for the correct response.

Is this an effect of construction of dams?

Yes or No

Loss of biodiversity

Yes/No

Displacement of people

Yes/No

Increase in the frequency of floods

Yes/No

Answer

1. C. Sample 2 and sample 4 are collected from the same water source.
2. A. Sample 1
3. Yes
Yes
No
4. Mentions that acidic water can kill many aquatic organisms.
For example
● Many aquatic organisms cannot survive in acidic water.
5. D. Washing Clothes
6. B. Forest 2
7. C. Forest 3
8. B. Rainforest
9. B. Increase in Global Warming
10. Yes
Yes
No

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Snake, Shrew

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A. Snake
B. Shrew
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D. Cricket and Grasshopper
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A. 1%
B. 2%
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3. Which of these represents the correct food web of the ecosystem?

Image

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Image
5. Which electromagnet will attract the maximum number of pins?
A. Electromagnet 1
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C. Electromagnet 3
D. Electromagnet 4
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Circle ‘Yes’ or ‘No’ for the correct response.

Should this be kept the same?

Yes or No

Thickness of the wires

Yes/No

Voltages of the batteries

Yes/No

Thickness of the iron bars

Yes/No

7. Label the north pole and south pole of the electromagnet in the diagram.

Image

8. Which of these devices works due to the magnetic effect of electric current?
A. LED bulb
B. Electric bell
C. Electric heater
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Read the following and answer any three questions from: (i) to (iv).
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  2. How many food chains are operating in the given food web?
     
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    OR
     
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Mr. Rakesh was helping her daughter Aruna at home understanding about the basics of reflection of light. He found the simplest way to convey the role of curved mirrors using stainless steel teaspoon. Aruna got surprised to know that virtual image is that which can be seen but cannot be obtained on the screen. Mr. Rakesh then explained the formation of image using Ray diagrams.
(i) What do you mean by reflection of light?
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or
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(iii) Name four types of chemical reactions.
or
(iv) Give example of precipitation reactions.

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    OR
     
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(ii) How does it help in extinguishing fire?
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A ray of light passes through a glass prism.

Image
9. When do the light rays get refracted?
Circle ‘Yes’ or ‘No’ to mark your responses.

When do the light rays get refracted?

Yes or No

As the light ray enters the prism from the air

Yes/No

As the light rays travel inside the prism

Yes/No

As the light rays move from the prism into the air

Yes/No

10. Why do leaves appear green?