INTRODUCTION - Chapter 4 Heat class 7 ncert solutions Science - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Question 1:

State similarities and differences between the laboratory thermometer and the clinical thermometer.

Answer:

Similarities:

(i) Both clinical and laboratory thermometers have long, narrow, uniform glass tubes.

(ii) The bulbs of both the thermometers have mercury in them.

Differences:

(i) The temperature range of clinical thermometers is from 35°C to 42°C while that of laboratory thermometer is from −10°C to 110°C.

(ii) Clinical thermometer is used to measure the temperature of a human body. However, laboratory thermometer cannot be used to measure the temperature of a human body.

(iii) The least count of both the thermometers differs.

(iv) Unlike clinical thermometer that can be tilted, laboratory thermometer is kept upright while reading the temperature values.

Question 2:

Give two examples each of conductors and insulators of heat.

Answer:

Two examples of conductors of heat are:

(i) Aluminium

(ii) Iron

Two examples of insulators of heat are:

(i) Wood

(ii) Plastic

Question 3:

Fill in the blanks:

(a) The hotness of an object is determined by its __ __.

(b) Temperature of boiling water cannot be measured by a

__ __ thermometer.

(c) Temperature is measured in degree ___ _.

(d) No medium is required for transfer of heat by the process of ___ _.

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

(f) Clothes of ___ _ colours absorb heat better than clothes of light colours.

Answer:

(a) The hotness of an object is determined by its __temperature__.

(b) Temperature of boiling water cannot be measured by a __clinical__ thermometer.

(c) Temperature is measured in degree __Celsius__.

(d) No medium is required for transfer of heat by the process of __radiation__.

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

(f) Clothes of __dark__ colours absorb heat better than clothes of light colours.