Latent Heat

Q. Explain why rails have gaps at specific distances.

Q.

A student heats a beaker containing ice and water. He measures the temperature of the content of the beaker as a function of time. Which of the following (Fig.) would correctly represent the result? Justify your choice.

1. 

2. 

3. 

4. 

Q. The heat energy required during the change of state from solid to liquid at constant temperature is called latent heat of .

1. fusion
2. vaporisation
3. freezing

Q.

The boiling point of pure water is ______ ${}^{o}C$, at normal atmospheric pressure.

Q.

A sample of water was found to have a boiling point of 101.5°C at normal (1 atm) atmospheric pressure.

1. Is water pure?
2. Will this water freeze at 0°C

Q.

How can we observe the change, of a given piece of matter, from one state to another?

Q. Heat always flows

ऊष्मा सदैव प्रवाहित होती है

1. From hotter object to colder object
   
   गर्म वस्तु से ठण्डी वस्तु की ओर
2. From colder object to hotter object
   
   ठण्डी वस्तु से गर्म वस्तु की ओर
3. From heavy object to lighter object
   
   भारी वस्तु से हल्की वस्तु की ओर
4. From lighter object to heavy object
   
   हल्की वस्तु से भारी वस्तु की ओर

Q.

In winters when the lakes start freezing, the weather becomes very pleasant in the surrounding region. Explain.

Q. Calculate the heat required to convert  $3kg$ of ice $at-{12}^{\circ }C$ kept in a calorimeter to steam at ${100}^{\circ }$ at atmospheric pressure. Given : specific heat of ice $=2100\times {10}^{5}J{kg}^{-1}{K}^{-1}$ , specific heat of water $=4186\times {10}^{3}J{kg}^{-1}{K}^{-1}$ , latent heat of fusion of $ce=3.35\times {10}^{5}J{kg}^{-1}$ and latent heat of steam $=2.256\times {10}^{6}J{kg}^{-1}$.

Q. Define:

1. Linear expansion of solids
2. Areal expansion of solids
3. Volumetric expansion of solids

Q. A quantity of heat required to change the unit mass of a solid substance to its liquid state, while the temperature remains constant, is known as

1. latent heat
2. latent heat of fusion
3. heat
4. specific heat

Q. Define:

1. Linear expansion of solids
2. Areal expansion of solids
3. Volumetric expansion of solids

Q.

Soft drinks bottles are kept in an ice-water mixture. Explain.

Q. Fig. shows the variation in temperature with time when some wax cools from the liquid phase to the solid phase. In which part of the curve, the wax will be in the liquid as well as in solid phase ?

1. PQ
2. QS
3. ST
4. can't say