Secondary School (English Medium) (5 to 8) कक्षा ८ - CBSE Question Bank Solutions for Science

Write True/False against the following statement.

Resources which are present in unlimited quantity in nature are called exhaustible natural resources.

Write True/False against the following statement.

Wildlife is an exhaustible natural resource.

Sunlight and air are inexhaustible natural resources. Comment.

Some natural resources are given below. Classify them into the exhaustible and inexhaustible natural resources.

Look at the figure where petroleum and natural gas deposits are shown. Why do we find oil layer above water layer?

Fill in the blanks and complete the story.

About 300 million years ago, the earth had dense ______ in low lying wetland areas. Due to natural processes like ______, these forests got buried under the ______. As more ______ deposited over them, they were compressed. The ______ also rose as they sank deeper and deeper. Under high ______ and high ______, dead plants got slowly converted into coal.

Match the items given in Column I with the items of Column II.

Imagine that all the exhaustible natural resources are exhausted by human activities. Do you think survival of living beings would be possible? If yes, why? If not, why not?

Why petrol is exhaustible natural resource, whereas sunlight is not? Explain.

Complete the crossword in figure with the help of the clues:

Across

1. Fuels obtained from dead remains of living organisms. (6, 5)

2. A process by which the various constituents of petroleum are separated. (8)

3. A porous black substance obtained from coal. (4)

4. Another name for motor fuel. (6)

Down

5. The substance obtained by carbonisation. (4)

6. Fuel for heavy motor vehicles. (6)

7. A petroleum product used for road surfacing. (7)

8. Dead remains of sea animals got converted into it. (9)

Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play

In the following figure, a boy is shown pushing the box from right to left. The force of friction will act on the box

We have two identical metal sheets. One of them is rubbed with sand paper and the other with ordinary paper. The one rubbed with sand paper shines more than the other. Give reason.

A list of mediums is given below.

1. wood
2. water
3. air
4. vacuum

In which of these mediums can sound travel?

Which of the following statements are correct?

1. Sound is produced by vibrations.
2. Sound requires a medium for propagation.
3. Light and sound both require a medium for propagation.
4. Sound travels slower than light.

Lightning can be seen the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s).

Name two musical instruments which produce sound by vibrating strings.

Electric current is to be passed from one body to another. For this purpose, the two bodies must be joined by 

During the construction of a building, the lightning conductor was left hanging in the air by mistake. Would the lightning conductor be still effective? Explain.

If air and cloud were good conductors of electricity, do you think lightning could occur? Explain.