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Page No 46: - Chapter 4 Heat class 7 ncert solutions Science - SaraNextGen [2024]


Question 4:

Match the following:

(i)

Land breeze blows during

(a)

summer

(ii)

Sea breeze blows during

(b)

winter

(iii)

Dark coloured clothes are preferred during

(c)

day

(iv)

Light coloured clothes are preferred during

(d)

night

Answer:

(i)

Land breeze blows during

(d)

night

(ii)

Sea breeze blows during

(c)

day

(iii)

Dark coloured clothes are preferred during

(b)

winter

(iv)

Light coloured clothes are preferred during

(a)

summer


Question 5:

Discuss why wearing more layers of clothing during winters keeps us warmer than wearing just one thick piece of clothing.

Answer:

During winters, we prefer wearing more layers of clothing than just one thick piece of clothing because air gets trapped in between the various clothing layers. Being a poor conductor of heat, air prevents heat loss from our body. Hence, layers of clothing keep us warmer than a single layer.

Question 6:

Look at Figure. Mark where the heat is being transferred by conduction, by convection and by radiation.

https://img-nm.mnimgs.com/img/study_content/curr/1/7/4/49/193/Chapter%204_html_m1ff903de.jpg

(i) Transfer of heat from burner to pan is by radiation.Answer:

(ii) Transfer of heat from pan to water is by conduction.

(iii) Transfer of heat within water is by convection.

Question 7:

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

Answer:

In places of hot climate, it is advised to paint the outer walls of houses as white because a light colour such as white reflects back most of the heat that falls on it. Hence, a light colour tends to keep the house cool.

Question 8:

One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be

(a) 80°C (b) more than 50°C but less than 80°C

(c) 20°C (d) between 30°C and 50°C

Answer:

(d)

The temperature of the mixture will be between 30°C and 50°C.

Also Read : Page-No-47:-Chapter-4-Heat-class-7-ncert-solutions-Science

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