Match the following Column A Column B a. Blowing air increases i. increase in intermolecular separation b. Increase in pressure increases ii. pendulum of a clock c. Thermal expansion iii. cooking utensils d. Invar iv. boiling point e. Pyrex glass v. evaporation

a. Blowing air increases - v. evaporation When air is blown above the surface of the liquid, the rate of evaporation increases. The moving air carries away the water molecules in the air. So the humidity is decreased and allows more water vapour to dissipate into the air. b. An increase in pressure increases - iv. boiling point The boiling point of liquid increases with an increase in pressure. At the boiling point, the pressure exerted by the vapour of a liquid is equal to the atmospheric pressure. The boiling point of a liquid depends on the surrounding atmospheric pressure. With the increase of atmospheric pressure, the boiling point of a liquid increase to increase the vapour pressure and make it equal to the atmospheric pressure. c. Thermal expansion - i. increase in intermolecular separation On heating, the average kinetic energy of the molecules increases and starts vibrating with large amplitude and hence increases the intermolecular separation. d. Invar - ii. pendulum of a clock Invar is an alloy of iron and nickel and having a small coefficient of linear expansion. The pendulum of invar make the clock neither to lose time in summer due to expansion nor to gain time in winter because of contraction. e. Pyrex - ii. cooking utensils The glassware used in kitchen are generally made up of pyrex glass. The reason is that the pyrex glass has a very low coefficient of cubical expansion, so the glassware on being heated, do not expand much and therefore they do not crack. Column A Column B a. Blowing air increases v. evaporation b. Increase in pressure increases iv. boiling point c. Thermal expansion i. increases the intermolecular separation d. Invar ii. pendulum of a clock e. Pyrex glass iii. cooking utensils

only the molecules at the surface escape out

all molecules of liquid begin to escape out.

the temperature of liquid rises by absorbing heat from surroundings.

the molecules get attracted within the liquid

E M B I B E

Concise Physics Middle School for Class 8>Chapter 6 - Heat Transfer>TEST YOURSELF>Q A

EASY

8th ICSE

IMPORTANT

Earn 100

Alcohol expands (less/more) than water.

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Important Questions on Heat Transfer

EASY

8th ICSE

IMPORTANT

Concise Physics Middle School for Class 8>Chapter 6 - Heat Transfer>TEST YOURSELF>Q A

Iron expands _____ (more/less) than copper.

HARD

8th ICSE

IMPORTANT

Concise Physics Middle School for Class 8>Chapter 6 - Heat Transfer>TEST YOURSELF>Q A

Match the following

Column A	Column B
a. Blowing air increases	i. increase in intermolecular separation
b. Increase in pressure increases	ii. pendulum of a clock
c. Thermal expansion	iii. cooking utensils
d. Invar	iv. boiling point
e. Pyrex glass	v. evaporation