List of top Science Questions asked in CBSE Class VIII

In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.
1. Squeezing a piece of lemon between the fingers to extract its juice.
2. Taking out paste from a toothpaste tube.
3. A load is suspended from a spring while its other end is on a hook fixed to a wall.
4. An athlete making a high jump to clear the bar at a certain height.

Match items in column A with those in column B. 

Explain why fossil fuels are exhaustible natural resources.

Give reasons.

1. Water is not used to control fires involving electrical equipment.
2. LPG is a better domestic fuel than wood.
3. Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not. 

Identify the part which vibrates to produce sound in the following instruments.

1. Dholak
2. Sitar
3. Flute

If wheat is sown in the kharif season, what would happen? Discuss.

You spill a bucket of soapy water on a marble floor accidently. Would it make it easier or more difficult for you to walk on the floor? Why

Write a short paragraph on the harmful effects of microorganisms.

The process that you saw in Activity 11.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transfered to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Match the organisms in Column A with their action in Column B.

Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Write a paragraph in your own words on each of the following.
1. Preparation of soil
2. Sowing
3. Weeding
4. Threshing

How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?

Suggest three measures to protect ourselves from lightning.

Describe the construction of a kaleidoscope.

Boojho stands at A just on the side of a plane mirror as shown in Fig. 

Can he see himself in the mirror? Also, can he see the image of objects situated at P, Q and R?

Give two differences between a zygote and a foetus.

Describe with the help of a diagram an instrument which can be used to detect a charged body.

Explain why sliding friction is less than static friction.

(a) Find out the position of the image of an object situated at A in the plane mirror.
(b) Can Paheli at B see this image?
(c) Can Boojho at C see this image?
(d) When Paheli moves from B to C, where does the image of A move?

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

1. Sound cannot travel in vacuum. (T/F)
2. The number of oscillations per second of a vibrating object is called its time period. (T/F)
3. If the amplitude of vibration is large, sound is feeble. (T/F)
4. For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
5. The lower the frequency of vibration, the higher is the pitch. (T/F)
6. Unwanted or unpleasant sound is termed as music. (T/F)
7. Noise pollution may cause partial hearing impairment. (T/F)

Explain why a charged body loses its charge if we touch it with our hand.

Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Sketch larynx and explain its function in your own words.

Fill in the blanks:

1. Fossil fuels are ___, ___ and ___.
2. Process of separation of different constituents from petroleum is called ___.
3. Least polluting fuel for vehicle is ___.