Calorimetry

The weather becomes mild during a snow storm because:

• one kilogram of ice on melting absorbs 336000 joules of heat energy from surroundings.

• one kilogram of water on freezing at 0o C releases 336000 joules of heat energy to the surroundings.

• one kilogram of water on freezing at 0 C releases 223000 joules of heat energy to the surroundings.

• one kilogram of ice on melting absorbs 223000 joules of heat energy from surroundings.

Which of the following statements are correct ? 1) The boiling point of a liquid decreases with the increase in pressure and increases with the decrease in pressure 2) The boiling point of a liquid decreases by the addition of impurities to it. 3) The melting point of a substance decreases by the presence of impurities in it. 4) The melting point of the substances which contract on melting (like ice) decreases by the increase in pressure.

• Only 1

• both 3 and 4

• all are correct

• only 2

When ice melts, its temperature:

• remains constant

• increases

• decreases

• changes

The quantity of heat energy required to raise the temperature of a body depends on :

• mass of the body

• nature of material of the body

• rise in temperature of the body

• all of the above

The changing from solid to vapour directly at a constant temperature is called :

• condensation

• regelation

• vapourisation

• sublimation

The specific latent heat of fusion of water is :

• 80 cal/g

• 2260 J/g

• 80 J/g

• 336 J/Kg

Plants are protected from wilting during summer due to:

• high specific latent heat of vaporisation of water

• low specific latent heat of vaporisation of water

• high specific heat capacity of water

• low specific heat capacity of water

Write the approximate value of specific heat capacity of water in S.I unit.

• 4200 J kg-1K-1

• 4.2 J kg-1K-1

• 4200 cal oC-1gm-1

• 4.2 cal oC-1kg-1

Icebergs are carried by ocean currents over very long distances due to:

• high specific heat capacity of water

• high specific latent heat of vapourisation of water

• high specific latent heat of fusion of ice

• low specific latent heat of fusion of ice

How much heat energy is required to melt 5 kg of ice? Specific latent heat of ice = 336 J/g.

• 168 J

• 1.68 x 103 J

• 16.8 x 103 J

• 1.68 x 106 J