List of top Science Questions asked in CBSE Class VIII

What is the difference between noise and music? Can music become noise sometimes?
An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms.
muscular, contact, non-contact, gravity, friction, shape, attraction
1.To stretch the bow, the archer applies a force that causes a change in its ___ .
2.The force applied by the archer to stretch the bow is an example of ___ force.
3.The type of force responsible for a change in the state of motion of the arrow is an example of a ___ force.
4.While the arrow moves towards its target, the forces acting on it are due to ___ and that due to ___ of air.
Fill in the blanks in the following statements.
1. To draw water from a well we have to ___ at the rope.
2. A charged body ___ an uncharged body towards it.
3. To move a loaded trolley we have to ___ it.
4. The north pole of a magnet ___ the north pole of another magnet.
Give two examples of situations in which applied force causes a change in the shape of an object.
Give two examples each of situations in which you push or pull to change the state of motion of objects.
The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
The table below shows the data on likely heights of boys and girls as they grow in age. Draw graphs showing height and age for both boys and girls on the same graph paper. What conclusions can be drawn from these graphs?

Word game : Use the clues to work out the words.
Across
3. Protruding voice box in boys
4. Glands without ducts
7. Endocrine gland attached to brain
8. Secretion of endocrine glands
9. Pancreatic hormone
10. Female hormone
Down
1. Male hormone
2. Secretes thyroxine
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence

Write notes on—
1. Adam’s apple.
2. Secondary sexual characters.
3. Sex determination in the unborn baby.

Choose the correct option.
The right meal for adolescents consists of

Choose the correct option.
Reproductive age in women starts when their

A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Choose the correct option.
Adolescents should be careful about what they eat, because
Fill in the blanks with suitable words.
  1. Time taken by an object to complete one oscillation is called ___ .
  2. Loudness is determined by the ___ of vibration.
  3. The unit of frequency is ___.
  4. Unwanted sound is called __________ .
  5. Shrillness of a sound is determined by the ___ of vibration.
Voice of which of the following is likely to have minimum frequency?
Choose the correct answer.
Sound can travel through
Explain why objects moving in fluids must have special shapes.
Explain why sportsmen use shoes with spikes.
Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
Alida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be
Fill in the blanks.
  1. Friction opposes the ___ between the surfaces in contact with each other.
  2. Friction depends on the ___ of surfaces.
  3. Friction produces ___.
  4. Sprinkling of powder on the carrom board ___ friction.
  5. Sliding friction is ___ than the static friction.
When we press the bulb of a dropper with its nozzle kept in water, air in the dropper is seen to escape in the form of bubbles. Once we release the pressure on the bulb, water gets filled in the dropper. The rise of water in the dropper is due to
A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.
What are sex hormones? Why are they named so? State their function.