Chapter 7 Solutions — Heat Transfer in Nature

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1. 1.
   Choose the correct option in each case.

   • (i) Your father bought a saucepan made of two different materials, A and B. The materials A and B have the following properties —
   • (a) Both A and B are good conductors of heat
   • (b) Both A and B are poor conductors of heat
   • (c) A is a good conductor and B is a poor conductor of heat
   • (d) A is a poor conductor and B is a good conductor of heat
   • (ii) Pins are…
2. 2.
   A shopkeeper serves you cold lassi in a tumbler. By chance, the tumbler had a small leak. You were given another tumbler by the shopkeeper to put the leaky tumbler in it. Will this arrangement help to keep the lassi cold for a longer time? Explain.
3. 3.
   State with reason(s) whether the following statements are True [T] or False [F].

   • (i) Heat transfer takes place in solids through convection.
   • (ii) Heat transfer through convection takes place by the actual movement of particles.
   • (iii) Areas with clay materials allow more seepage of water than those with sandy materials.
   • (iv) The movement of cooler air from land to sea is called land breeze.
4. 4.
   Some ice cubes placed in a dish melt into water after sometime. Where do the ice cubes get heat for this transformation?
5. 5.
   A burning incense stick is fixed, pointing downwards. In which direction would the smoke from the incense stick move? Show the movement of smoke with a diagram.
6. 6.
   Two test tubes with water are heated by a candle flame as shown in Fig. 7.16. Which thermometers (Fig. 7.16a or Fig. 7.16b) will record a higher temperature? Explain.
7. 7.
   Why are hollow bricks used to construct the outer walls of houses in hot regions?
8. 8.
   Explain how large water bodies prevent extreme temperature in areas around them.
9. 9.
   Explain how water seeps through the surface of the Earth and gets stored as groundwater.
10. 10.
    The water cycle helps in the redistribution and replenishment of water on the Earth. Justify the statement.