Engineering Questions with Answers - Multiple Choice Questions

# Separation Processes MCQ’s – Precipitation

1 - Question

Precipitation is opposite of what separation technique?
a) Distillation
b) Solution crystallization
c) Melt crystallization
d) Zone melting

View Answer

Answer: b
Explanation: In solution crystallization a solution is cooled or partially to make the solution exceed in its solubility sufficiently to make the solute crystallize. So it is the opposite of solution crystallization.

2 - Question

Precipitation is applicable for what types of solutes?
a) Insoluble
b) Soluble
c) Sparingly soluble
d) Both insoluble and soluble

View Answer

Answer: c
Explanation: Precipitation is applicable only for sparingly soluble solutes so that they precipitate out easily.

3 - Question

Why does the resulting shapes maybe far away from what corresponds to minimum gibbs free energy?
a) Because they come out of a solution
b) Because they might contain moisture
c) Because they are formed at considerable super saturation
d) Because they contain impurities from solution

View Answer

Answer: c
Explanation: The resulting shapes maybe far away from what corresponds to minimum gibbs free energy which depends on particle size and interfacial tension b Because they are formed at considerable super saturation.

4 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 30 seconds, what is the number of crystals per unit volume of mother liquor?
a) 6*108
b) 6*109
c) 1.5*109
d) 1.5*108

View Answer

Answer: b
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 6*109.

5 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 3seconds, what is the number of crystals per unit volume of mother liquor?
a) 6*108
b) 6*109
c) 1.5*109
d) 1.5*108

View Answer

Answer: a
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 6*108.

6 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 75seconds, what is the number of crystals per unit volume of mother liquor?
a) 6*108
b) 6*109
c) 1.5*109
d) 1.5*108

View Answer

Answer: c
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 1.5*109.

7 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 40 seconds, what is the number of crystals per unit volume of mother liquor?
a) 8*108
b) 8*109
c) 9*109
d) 9*108

View Answer

Answer: b
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 8*109.

8 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 45 seconds, what is the number of crystals per unit volume of mother liquor?
a) 8*108
b) 8*109
c) 9*109
d) 9*108

View Answer

Answer: c
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 9*109.

9 - Question

If the nucleation rate is Bo=6.67*108nuclei/Ls and the induction time T= 30 seconds, what is the number of crystals per unit volume of mother liquor?
a) 6*108
b) 6*109
c) 6*1010
d) 6.67*109

View Answer

Answer: c
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 6*1010.

10 - Question

If the nucleation rate is Bo=2*108nuclei/Ls and the induction time T= 12 seconds, what is the number of crystals per unit volume of mother liquor?
a) 23*108
b) 6*109
c) 56*109
d) 24*108

View Answer

Answer: d
Explanation: Number of crystals per unit volume of mother liquor= Bo*T= 24*108.