Question Answers: NCERT Class 8 Science

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

Sketch larynx and explain its function in your own words.

Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

Make a labelled diagram of a candle flame.

What is metamorphosis? Give examples.

The following Table shows the total power shortage in India from 1991– 1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

Make sketches of animal and plant cells. State three differences between them.

What is a constellation? Name any two constellations.

Describe the construction of a kaleidoscope.

Complete the crossword with the help of clues given below:
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.

Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.

Indicate whether the following statements are True (T) or False (F):
(a) Oviparous animals give birth to young ones.                                    ( )
(b) Each sperm is a single cell.                                                              ( )
(c) External fertilization takes place in frog.                                           ( )
(d) A new human individual develops from a cell called gamete.          ( )
(e) Egg laid after fertilization is made up of a single cell.                       ( )
(f) Amoeba reproduces by budding.                                                       ( )
(g) Fertilization is necessary even in asexual reproduction.                  ( )
(h) Binary fission is a method of asexual reproduction.                         ( )
(i) A zygote is formed as a result of fertilization.                                    ( )
(j) An embryo is made up of a single cell.                                              ( )

What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

What are the different ways in which water gets contaminated ?

Describe the construction of a kaleidoscope.

The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.

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.

A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.

Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

Which of the following is NOT a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet