ICSE ICSE Class 8 - CISCE Question Bank Solutions for Physics

In evaporation

The rate of evaporation of a liquid increases when:

During boiling or vaporization

The boiling point of a liquid is increased by

Do all the molecules of a liquid take part in evaporation? If not, explain your answer.

No heat is supplied to a liquid during evaporation. How does then the liquid change into its vapours?

Comment on the statement ‘evaporation is a surface phenomenon’.

Why is cooling produced when a liquid evaporates?

Give reason for the increase in rate of evaporation of a liquid when air is blown above the liquid.

Give reason for the increase in rate of evaporation of a liquid when surface area of liquid is increased.

Give reason for the increase in the rate of evaporation of a liquid when temperature of liquid is increased.

What is boiling? Explain it on the basis of molecular motion?

What is the change in average kinetic energy of molecules of a liquid during boiling at its boiling point?

How is the heat energy supplied to a liquid used during boiling at a fixed temperature?

Name two ways of change of liquid state to the vapour state and distinguish them.

When sound propagates in air, it does not carry energy with it.

In a longitudinal wave, compression and rarefaction are formed.

The distance from one compression to nearest rarefaction is called wavelength.

The frequency is measured in second.

The quality of a sound depends on the amplitude of wave.