Effect of High Latent Heat of Fusion of Ice

Q.

The temperature of the surrounding starts falling when ice in a frozen lake starts melting. Give reason.

Q.

Water in lakes and ponds do not freeze at once in cold countries. Give reason.

Q.

It is generally cold after a hail-storm than during and before the hail-storm. Give reason.

Q.

How many grams of ice at -14^oC are needed to cool 200g of water from 25^oC to 10^oC? (Take, specific heat of ice=0.5calg^-1oC^-1 and latent heat of ice =80calg^-1)

1. 20g

2. 27g

3. 30g

4. 31g

Q.

Snow on the mountains does not melt all at once. Choose the correct reason for the above:

1. Low specific heat of fusion of ice

2. High latent heat of fusion

3. Low boiling point of water

4. High boiling point of water

Q.

Give two important effects of heat.

Q.

A piece of ice falls from a height h so that $\mathrm{t}$ melts completely. Only one-quarter of the heat produced is absorbed $\mathrm{b}$ the ice, and all energy of ice gets converted into heat during its fall. The value of $\mathrm{h}$ is? (Latent heat of force is $3.4\times {10}^5\mathrm{J}/\mathrm{k}$ and $\mathrm{g}=10\mathrm{N}/\mathrm{kg}$).

1. $34\mathrm{km}$

2. $68\mathrm{km}$

3. $136\mathrm{km}$

4. $544\mathrm{km}$

Q.

During melting heat is

1. Dismissed

2. Absorbed

3. Any of (a) and (b)

4. None of these

Q.

Why does weather become pleasant when freezing starts in cold countries?

Q. When the ice from a frozen lake starts to melt, the temperature of the surroundings will

1. fall to $0{}^{\circ }\text{C}$ instantly
2. decrease
3. increase
4. remain the same

Q. From what height a piece of ice $\left(0^{o}C\right)$ fall so that melts completely? Only one-quarter of the energy produced is absorbed by the ice as heat.(Latent heat of ice $=3.4\times {10}^{5}J{kg}^{-1},g=10{m/s}^2$)

Q.

Assertion: Wise farmers water their fields in the evening if the forecast is severe frost.

Reason: The ice has the highest specific latent heat of fusion.

1. Both ‘A’ and ‘R’ are correct and ‘R’ is the correct explanation of ‘A’.

2. Both ‘A’ and ‘R’ are correct, but ‘R’ is not the correct explanation of ‘A’.

3. ‘A’ is correct, but ‘R’ is incorrect

4. ‘A’ is incorrect, but ‘R’ is correct

Q. Snow on mountains does not melt all at once, because of the _______.

1. low latent heat of fusion of ice
2. high latent heat of fusion of ice
3. low boiling point of water
4. high melting point of ice

Q.

$80\mathrm{g}$ of water at ${10}^{°}\mathrm{C}$ is mixed with steam at${100}^{°}\mathrm{C}$. The amount of water present after it acquires a temperature of ${40}^{°}\mathrm{C}$ is?

Q. It is generally cold after a hail-storm than during and before the hail-storm. Give reason.

Q.

Describe how the change of state from a liquid to gas takes place?

Q.

When ice changes into water, Heat is released.

1. True
2. False

Q. The process of a liquid changing into a solid is called:

1. sublimation
2. evaporation
3. precipitation
4. freezing

Q. The snow on mountains does not melt all at once.

1. False
2. True

Q. A composite block is made of slabs A, B, C, D and E of different thermal conductivities(given in terms of a constant K) and sizes (given in terms of length, L) as shown in the figure. All slabs are of same width. Heat 'Q' flows only from left to right through the blocks. Then in steady state.

1. Heat flow through A and E slabs are same
2. Heat flow through slab E is maximum
3. Temperature difference across slab is smallest
4. Heat flow through C$=$ heat flow through B$+$ heat flow through D

Q.

The weather becomes somewhat pleasant in cold country when snow is actually falling

Q. Explain why heat systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water.

Q. Water and ice can exist together at 0${}^{\circ }$$C$

1. True
2. False

Q. It becomes extremely cold during snow fall. Explain why.

Q. An amount of energy is added to ice, raising its temperature from $-{10}^{0}C$ to $-5^{0}C$. A larger amount of energy is added to the same mass of water, raising its temperature from ${15}^{0}C$ to ${20}^{0}C$. From these results, what would you conclude?

1. The latent heat of fusion of ice delivers some energy to the system.
2. The specific heat of ice is less than that of water.
3. The specific heat of ice is greater than that of water.
4. More information is needed to draw any conclusion.
5. Overcoming the latent heat of fusion of ice requires an input of energy.