ICSE ICSE Class 7 - CISCE Question Bank Solutions for Physics

Fill in the blank

Black and dull surfaces are ______ of heat.

Select the correct alternative

The temperature of pure melting ice is

Select the correct alternative

Which of the statement is correct

Name the instrument used to measure the temperature of a body.

The fig. shows a glass tumbler containing hot milk which is placed in a tub of cold water. State the direction in which heat will flow.

What do you understand by thermal expansion of a substance ?

Name two substances which expand on heating.

Why do telephone wires sag in summer ?

Iron rims are heated before they are fixed on the wooden wheels. Explain the reason.

Why are gaps left between successive rails on a railway track ?

A glass stopper stuck in the neck of a bottle can be removed by pouring hot water on the neck of the bottle. Explain why ?

Why is a cement floor laid in small pieces with gaps in between?

One end of a steel girder in a bridge is not fixed, but is kept on roliers. Give the reason.

Describe one experiment to show that liquids expand on heating.

State one application of thermal expansion of liquids.

Describe an experiment to show that air expands on heating.

An empty glass bottle is fitted with a narrow tube at its mouth. The open end of the tube is kept in a beaker containing water. When the bottle is heated, bubbles of air are seen escaping into the water. Explain the reason. 

State which expands more, when heated to the same temperature : solid, liquid or gas ?

What are the good and bad conductors of heat ? Give two examples of each.

Name a liquid which is a good conductor of heat.