Latent Heat of Vaporisation

Q. Heat needed to melt $1kg$ of ice at its melting point is:

1. 40 J
2. $3.35\times {10}^5$ J
3. 80 J
4. 800 J

Q.

What causes more severe burns, steam or boiling water?

1. Steam

2. Boiling water

3. Steam and boiling water.

4. Cold water

Q. The temperature of a substance remains same during the change of state due to __________.

1. latent heat
2. sensible heat
3. less supply of heat
4. direct heat

Q.

What happens when you pour some acetone on your palm?

1. The particles lose energy and evaporate causing the palm to feel cool.

2. The particles gain energy from the palms or surroundings and evapoarte causing palm to feel cool.

3. The particles lose energy from the palms and condensate causing the palm to feel hot.

4. All the options are correct.

Q. The amount of heat needed to melt $2kg$ of ice at its melting point, when latent heat of ice is $80cal/g$, is _____.
$(1cal=4.184J)$

1. $40\times {10}^{5}J$
2. $6.7\times {10}^{5}J$
3. $3.35\times {10}^{5}J$
4. $1.675\times {10}^{5}J$

Q.

A solid of mass 150 g at 200 °C is placed in 0.4 kg of water at 20 °C till a constant temperature is attained. If the S.H.C of the solid is 0.5 Jg^-1 K^-1, find the resulting temperature of the mixture.

Q.

One day you were boiling water for making tea, you observed that at a certain point, the temperature of the solution became constant. Identify a correct reason.

1. All the heat passed to the water was getting used to change the state.

2. At that point, water started boiling.

3. Changing state of matter requires energy.

4. All the options are correct.

Q. Latent heat of vaporisation is the amount of heat required to:

1. Raise the temperature of 1 kg of a substance by 1 K
2. Raise the temperature of a substance by 1 K
3. Change the phase of a substance from solid to liquid
4. Change phase of a substance from liquid to gas