1. What is the melting point of a substance?
A.
The temperature at which a liquid changes into a gas
B.
The temperature at which a solid changes into a liquid
C.
The temperature at which a gas changes into a liquid
D.
The temperature at which a liquid changes into a solid
Correct Answer:
The temperature at which a solid changes into a liquid
Explanation:
The melting point is the temperature at which a solid changes into a liquid.
2. At its melting point, a pure solid and its liquid generally exist together in what condition?
A.
Chemical equilibrium
B.
Thermal decomposition
C.
Phase equilibrium
D.
Complete evaporation
Correct Answer:
Phase equilibrium
Explanation:
At the melting point, the solid and liquid phases coexist in phase equilibrium.
3. Which change of state occurs at the melting point?
A.
Solid to liquid
B.
Liquid to gas
C.
Gas to solid
D.
Liquid to solid
Correct Answer:
Solid to liquid
Explanation:
Melting is the change of state in which a solid becomes a liquid at its melting point.
4. The melting point of a substance is normally specified at which condition?
A.
A particular pressure
B.
Zero temperature
C.
Constant volume only
D.
Complete vacuum only
Correct Answer:
A particular pressure
Explanation:
Melting point depends on pressure, so it is defined or reported at a specified pressure, commonly one atmosphere.
5. What happens to a pure solid when it reaches its melting point under suitable pressure?
A.
It begins changing into a liquid
B.
It immediately changes into a gas
C.
It becomes colder without changing state
D.
It changes into another solid only
Correct Answer:
It begins changing into a liquid
Explanation:
At its melting point, a pure solid starts undergoing the solid-to-liquid phase change.
6. Which statement correctly defines the melting point of ice?
A.
The temperature at which ice changes into water
B.
The temperature at which water changes into steam
C.
The temperature at which steam changes into water
D.
The temperature at which water changes into ice
Correct Answer:
The temperature at which ice changes into water
Explanation:
For ice, the melting point is the temperature at which solid ice changes into liquid water at a specified pressure.
7. Melting point refers to the temperature of transition between which two states?
A.
Gas and plasma
B.
Solid and liquid
C.
Liquid and gas
D.
Solid and gas
Correct Answer:
Solid and liquid
Explanation:
The melting point is the temperature at which the solid and liquid states are in transition.
8. Which process is the reverse of melting?
A.
Boiling
B.
Sublimation
C.
Freezing
D.
Evaporation
Correct Answer:
Freezing
Explanation:
Freezing is the reverse of melting, in which a liquid changes into a solid.
9. At the melting point, added heat is mainly used to cause what change?
A.
A change from solid to liquid
B.
A change from liquid to gas
C.
A change from gas to liquid
D.
A change from liquid to solid
Correct Answer:
A change from solid to liquid
Explanation:
At the melting point, heat supplied to a substance enables the solid-to-liquid phase change.
10. Which of the following is an example of melting?
A.
Water turning into ice
B.
Ice turning into water
C.
Water turning into vapor
D.
Vapor turning into water
Correct Answer:
Ice turning into water
Explanation:
Ice turning into water is melting because the substance changes from the solid state to the liquid state.
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