ICSE ICSE Class 7 - CISCE Question Bank Solutions

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.

Name a solid which is a good conductor of heat.

Select good and bad conductors of heat from the following:
copper, mercury, wood, iron, air, saw-dust, cardboard, silver, plastic, wool.

Why do we use cooking utensils made up of copper.

Why is a tea kettle provided with an ebonite handle?

In summer, ice is kept wrapped in a gunny bag. Explain the reason.

Why is an oven made of double walls with the space in between filled with cork ?

Explain why  we wear woolen clothes in winter.

Explain why  the water pipes are covered with cotton during very cold weather.