Factors Affecting Melting Point

Q.

What happens to the temperature of a substance while it is changing its state?

Q.

State the effect of presence of impurity on the melting point of ice. Give one use of it.

Q.

State the effect of increase of pressure on the melting point of ice.

Q. The heating curve for ice initially at a particular pressure is given.

Choose the correct heating curve for the ice initially at $0{}^{\circ }\text{C}$, if the pressure is decreased.

1. 

2. 

3. 

4. 

Q.

What is the steam point of water?

1. 35°C

2. 99°C

3. 273 K

4. 373 K

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

1. increase
2. decrease
3. remain same

Q.

What is the boiling point of water on the Celsius scale?

Q.

Specific heat capacity of substance A is $3.8\mathrm{J}/\mathrm{gK}$, whereas the specific heat capacity of substance B is $0.4\mathrm{J}/\mathrm{gK}$

(i) Which of the two is good conductor of heat?

(ii) How is one led to the above conclusion?

(iii) If substances A and B are liquid, then which one would be more useful in car radiators?

Q.

What happens to the melting point of ice when we increase the pressure?

1. Decreases

2. Increases

3. Remains the same

4. None of these

Q. Why is it wrong in taking the melting point of ice and the boiling point of water as standard fixed points (as was originally done in the celsius scale)?

Q. An ice block at zero degree Celsius and mass M is dropped from the height h, that the loss in gravitational potential energy of block, is exactly equal to the heat required to just completely melt the ice. The value of h is ?

1. $8m$
2. $8km$
3. $33.6m$
4. $33.6km$

Q. The melting point of ice can fluctuate due to various reasons. Pick the correct reasons from the following:

1. It decreases with increase in altitude.
2. It decreases with increase in pressure.
3. It increases with the addition of impurities.
4. It decreases with the addition of impurities.

Q. In an energy recycling process, $Xg$ of steam at ${100}^{0}C$ becomes water at ${100}^{0}C$ which converts $Yg$ of Ice at $0^{0}C$ into water at ${100}^{0}C$ . The ratio of $X/Y$ will be

1. $\frac{1}{3}$
2. $\frac{2}{3}$
3. $3$
4. $2$

Q. Two blocks of ice when pressed together joined to form a block because

1. of heat produced during pressing.
2. of cold produced during pressing.
3. melting point of ice increases with increase in pressure.
4. melting point of ice decreases with increase in pressure.

Q.

A block of ice at $-{10}^{o}C$ is slowly heated and converted to steam at ${100}^{o}C.$ Which of the following curves represents the phenomenon qualitatively?

1. 

2. 

3. 

4. 

Q.

A smart farmer fills up his field entirely with water on an extremely cold night. Why?

1. As water has low SHC and liberates a large amount of heat on cooling

2. As water has high SHC and liberates a large amount of heat on cooling

3. As water has low SHC and liberates a small amount of heat on cooling

4. As water has high SHC and liberates a small amount of heat on cooling

5. As water is a very good conductor of heat and hence transmit large amount of heat

Q. When salt is properly mixed with ice, the melting point of ice

1. is lowered
2. is raised
3. remains the same
4. becomes infinte

Q. Assertion :In change of state from solid to liquid the temperature decreases util the entire amount of the solid substance melts Reason: The phenomenon of refreezing is called melting

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

In which of the following substances, the melting point increases with the increase in pressure.

1. Ice

2. Wax

3. Lead

4. Polythene

Q. Which among these contracts on melting?

1. Ice
2. Lead
3. Wax
4. Iron

Q. When salt is properly mixed with ice, the melting point of ice

1. is lowered
2. is raised
3. remains the same
4. becomes infinite

Q. A teacher demonstrates an experiment to a class. A boiling tube is filled with water and some ice cubes are trapped at the bottom of the tube. The teacher then heats the boiling tube in the position shown until the water at the top boils.
The ice does not melt.
What does this demonstrate?

1. Water is a good conductor of thermal energy
2. Water is a good convector of thermal energy
3. Water is a poor conductor of thermal energy
4. Water is a poor convector of thermal energy

Q. A piece of ice at $0^{\circ }C$ is added to a vessel containing water at $0^{\circ }C$, then

1. all of the ice will melt
2. some ice will melt
3. no ice will melt
4. the temperature will decrease further

Q. Melting point of Tungsten metal is ______ ${}^{o}C$

1. $3422$
2. $3322$
3. $3420$
4. $3430$

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

1. increase
2. decrease
3. remain same

Q. The water can be made to boil even at $0^{\circ }C$ if the pressure of surrounding is

1. 76 cm of Hg
2. 5 cm of Hg
3. 0.1 cm of Hg
4. 56 cm of Hg

Q.

If an iron chair and a wooden chair are kept in the sun for a sufficient amount of time and then, are touched, which of them will appear warmer?

1. Wooden chair

2. Both will appear equally warmer

3. Iron chair

4. Depends on the temperature of the surroundings

Q. A gas thermometer measures the temperature from the variation of pressure of sample of gas. If the pressure measured at the melting point of lead is $2.20$ times the pressure measured at the triple point of water, find the melting point of lead.

Q. Fill in the blanks :

1. increases
2. decreases
   
3. does not change
4. can't say

Q. Why two blocks of ice when put together and compressed become a single block of ice?

1. Ice blocks attract each other to form a bond
2. Melting point of ice increases when pressure is increased
3. Melting point of ice decrease when pressure is increased
4. Latent heat of fusion of ice is high