# Separation Processes Questions and Answers – Precipitation

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This set of Separation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Precipitation”.

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

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

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

3. 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

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. 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

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

5. 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

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

6. 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

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

7. 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

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

8. 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

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

9. 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

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

10. 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 