Engineering Questions with Answers - Multiple Choice Questions

# Separation Processes MCQ’s – Multiphase Systems

1 - Question

What is the third phase in all the two phase systems?
b) The interface
c) The container
d) The atmosphere
Explanation: The third phase is the container which selected as inert for separation purposes.

2 - Question

How to separate vapor-liquid-liquid system?
a) Fractional distillation
b) Fractional crystallization
c) Zone melting
d) Three phase isothermal flash
Explanation: A three phase isothermal flash is used to separate vapor-liquid-liquid system.

3 - Question

Why are calculations for three phase flash difficult?
a) Because of strong dependency of K values on liquid phase composition when two immiscible liquids are present
b) Because of strong dependency of K values on vapor phase composition when two immiscible liquids are present
c) Because of strong dependency of K values on liquid phase composition when two miscible liquids are present
d) Because of strong dependency of K values on liquid phase composition when three immiscible liquids are present
Explanation: The calculations of three phase flash are difficult due to strong dependency of K values on liquid phase composition when two immiscible liquids are present.

4 - Question

What is the enthalpy balance for three phase system?
a) hFF + Q =hvV + hLL(1) + hLL(2)
b) hFF =hvV + hLL(1) + hLLL(2)
c) hFF – Q =hvV + hL(1) + hLLL(2)
d) hFF + Q =hvV + hLL + hLLL
Explanation: The correct enthalpy balance is hFF + Q =hvV + hLL(1) + hLL(2).

5 - Question

The calculations of multiphase system are made by:
a) Graph
b) Hand calculations
c) Trial and error
d) Process simulators
Explanation: Calculations of multiphase system are made by process simulators.

6 - Question

If at a certain pressure the vapor pressure of water is 4.74pisa and the mole fraction of water is 0.923, find out the crystallizer pressure.
a) 2.5pisa
b) 4.38pisa
c) 4.56pisa
d) 4.76pisa
Explanation: Roult’s law is used P=psxh20. Hence P=4.74*0.923=4.38pisa.

7 - Question

If at a certain pressure the vapor pressure of water is 8pisa and the mole fraction of water is 0.9, find out the crystallizer pressure.
a) 0.64pisa
b) 7.2pisa
c) 0.66pisa
d) 0.81pisa
Explanation: Roult’s law is used P=psxh20. Hence P=8*0.9=7.2pisa

8 - Question

If at a certain pressure the vapor pressure of water is 6pisa and the mole fraction of water is 0.7, find out the crystallizer pressure.
a) 3.3pisa
b) 3.5pisa
c) 3.96pisa
d) 4.2pisa
Explanation: Roult’s law is used P=psxh20. Hence P=6*0.7=4.2pisa.

9 - Question

If at a certain pressure the vapor pressure of water is 2pisa and the mole fraction of water is 0.9, find out the crystallizer pressure.
a) 0.45pisa
b) 1.8pisa
c) 3.6pisa
d) 0.81pisa
Explanation: Roult’s law is used P=psxh20. Hence P=2*0.9=1.8pisa

10 - Question

If at a certain pressure the vapor pressure of water is 10pisa and the mole fraction of water is 0.8, find out the crystallizer pressure.
a) 5pisa
b) 6pisa
c) 7pisa
d) 8pisa