Question

In the preparation of soap, sodium chloride causes:
(a) complete saponification.
(b) complete hydrolysis.
(c) complete neutralization.
(d) complete precipitation.

Answer 1

Once the saponification reaction is complete, sodium chloride is added to precipitate the soap. Therefore, option (d) is correct, i.e. to complete the precipitation.

Answer 2

 common Salt is added  to precipitate out the soap from the aqueous solution.
when we add salt to solution, then the solubility of soap decreases due to which all the soap separates out from the solution in the form of solid.

Conclusion:
In the preparation of soap, sodium chloride causes:
option d is the correct Answer. ---- for complete precipitation.