Worksheet Solutions: Heat - Science Class 7

Q.1. True/False
(i) Temperature of boiling water cannot be measured by a clinical thermometer.

True

(ii) Medium is required for transfer of heat by the process of radiation.

False

(iii) Clothes of dark colours absorb heat better than clothes of light colours.

True

(iv) Light coloured clothes are preferred during summer.

True

(v) We should hold the thermometer by the bulb while holding it.

False

(vi) The bulb of laboratory thermometer should not touch the bottom or the sides of the container.

True

Q.2. Fill in the blanks.
(i)  The hotness of an object is determined by its ____.

temperature

(ii) Temperature is measured in degree ____.

celsius

(iii) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ____.

conduction

(iv) Land breeze blows during ____.

night

(v) Sea breeze blows during ____.

day

(vi) Dark coloured clothes are preferred during ____.

winter

(vii) Poor conductors are known as ____.

insulators

Q.3. What is the use of the kink in clinical thermometer?

It prevents mercury level from falling on its own.

Q.4. Does transfer of heat by radiation require any medium?

The transfer of heat by radiation does not require any medium.

Q.5. The transfer of heat by radiation does not require any medium.

Clinical thermometer cannot be used to measure high temperatures because the range of this thermometer is from 35°C to 42°C only.

Q.6. What is the concern associated with the use of mercury thermometer?

There is a lot of concern over the use of mercury in thermometers. Mercury is a toxic substance and is very difficult to dispose of if a thermometer breaks.

Q.7. In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

In places of hot climate it is advised that the outer walls of houses be painted white because light color reflects most of the heat that falls on them and thus keep the house cool.

Q.8. How water gets heated when kept on flame?

When water is heated, the water near the flame gets hot. Hot water rises up. The cold water from the sides moves down towards the source of heat. This water also gets hot and rises and water from the sides moves down. This process continues till the whole water gets heated. This mode of heat transfer is known as convection.

Q.9. Why does the mercury not fall or rise in a clinical thermometer when taken out of the mouth?

Clinical thermometer has kink near the bulb prevents mercury level from falling on its own.

Q.10. Explain land breeze.

At night, the water cools down more slowly than the land. So, the cool air from the land moves towards the sea. This is called the land breeze.

Q.11. Explain the construction of clinical thermometer.

A clinical thermometer consists of a long, narrow, uniform glass tube. It has a bulb at one end. This bulb contains mercury. Outside the bulb, a small shining thread of mercury can be seen.

Q.12. Which device is used to measure temperature?

Thermometer is used to measure temperature.

Q.13. What is the unit of temperature as adopted by India?

India has adopted the Celsius Scale.

Q.14. What is the range of a laboratory thermometer?

The range of a laboratory thermometer is generally from –10°C to 110°C.

Q.15. How does heat flow from one object to another?

Heat flows from a hotter object to a colder object.

Q.16. Do all hot bodies radiate heat?

Yes, all hot bodies radiate heat.

Q.17. What do you mean by temperature?

A reliable measure of the hotness of an object is its temperature.

Q.18. Will heat transfer if the temperature of two objects is the same?

Heat will not be transferred if the temperature of two objects is the same.

Q.19. How does heat transfer in solids?

In solids, generally, the heat is transferred by the process of conduction.

Q.20. What is Conduction?

The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.