# Chemical Process Calculation Questions and Answers – Phase diagrams and Phase Rule-I

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This set of Chemical Process Calculation Multiple Choice Questions & Answers (MCQs) focuses on “Phase diagrams and Phase Rule-I”.

1. Representation of the different phase of a compound on a two or three dimensional graph is
a) Block diagram
b) Equilibrium diagram
c) Phase diagram
d) None of the mentioned

Explanation: Representation of the different phase of a compound on a two or three dimensional graph is called Phase diagram.

2. A non-condensable gas is found
a) Above the critical point
b) Below the critical point
c) On the critical point
d) None of the mentioned

Explanation: A non-condensable gas is found above the critical point.

3. Incorrect statement about a phase diagram is
a) Phase diagram are based on equilibrium conditions
b) For phase equilibrium, it is assumed that the phase doesn`t remain invariant
c) Phase diagrams enable to view the properties of two or more phases as a function of temperature, pressure and other variable
d) None of the mentioned

Explanation: For phase equilibrium, it is assumed that the phase remains invariant.
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4. The one P-T-V combination at which solid, liquid and vapour are in equilibrium, is called
a) Critical point
b) Triple point
c) Saturation point
d) None of the mentioned

Explanation: The one P-T-V combination at which solid, liquid and vapour are in equilibrium, is called Triple point.

5. If the vapour and liquid of a pure component are in equilibrium, the equilibrium pressure is called
a) Partial pressure
b) Vapour pressure
c) Liquid pressure
d) None of the mentioned

Explanation: If the vapour and liquid of a pure component are in equilibrium, the equilibrium pressure is called Vapour pressure.

6. At a given temperature there is only ________ pressure at which the vapour and liquid phases of a pure substances may exist in equilibrium.
a) Three
b) Two
c) One
d) None of the mentioned

Explanation: At a given temperature there is only one pressure at which the vapour and liquid phases of a pure substances may exist in equilibrium.

7. The change of phase from liquid to vapour is called
a) Boiling
b) Melting
c) Condensation
d) None of the mentioned

Explanation: The change of phase from liquid to vapour is called Boiling.

8. __________ is the temperature at which a liquid just start to vaporize.
a) Critical point
b) Bubble point
c) Triple point
d) Saturation point

Explanation: Bubble point is the temperature at which a liquid just start to vaporize.

9. Find the incorrect statement for condensation
a) The change of phase from vapour to liquid
b) Occurs at constant temperature and pressure
c) The process appears as a point in in a P-T diagram
d) All of the mentioned

Explanation: All a, b & c are correct for condensation.

10.______ is the temperature at which the vapour just begins to condense at a specified pressure, that is the value temperature along the vapour pressure curve.
a) Dew point
b) Bubble point
c) Triple point
d) Critical point