Question

Assertion:
When sodium chloride is dissolved in water, both cation and anion undergo hydrolysis.
Reason:
The solution has ${\text{pH = 7}}$ at ${25^ \circ }{\text{C}}$.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is incorrect but Reason is correct.
D. Both Assertion and Reason are incorrect.

Answer 1

Salt is the product formed from the reaction between an acid and a base. This reaction is called a neutralization reaction. The given compound sodium chloride is an example of a salt. These salts undergo hydrolysis to produce acids and bases.

Complete answer:
Water has a polar character. Hydrolysis is a process in which an ionic compound is dissolved in water to dissociate into its corresponding ions. The reaction showing the dissociation of water is given below:
${{\text{H}}_{\text{2}}}{\text{O}} \rightleftharpoons {{\text{H}}^ + } + {\text{O}}{{\text{H}}^ - }$
When a strong acid reacts with a strong base, salt is formed. This salt solution has a ${\text{pH}}$ of$7$. The salt, when reacted with water, has neither acidic properties nor basic properties. When sodium chloride is dissociated, it forms ${\text{N}}{{\text{a}}^ + }$ and ${\text{C}}{{\text{l}}^ - }$ ions.
${\text{NaCl}} \rightleftharpoons {\text{N}}{{\text{a}}^ + } + {\text{C}}{{\text{l}}^ - }$
But these ions do not get hydrolyzed, i.e. they have no ability to react with ${{\text{H}}^ + }$ and ${\text{O}}{{\text{H}}^ - }$ ions which are produced by the dissociation of water. Thus the concentration of ${{\text{H}}^ + }$ and ${\text{O}}{{\text{H}}^ - }$ does not change, thereby no change in the ${\text{pH}}$, i.e. it remains neutral.
Thus we can say that both ${\text{N}}{{\text{a}}^ + }$ and ${\text{C}}{{\text{l}}^ - }$ ions do not get hydrated when ${\text{NaCl}}$ gets dissolved in water. But the ${\text{pH}}$ of the solution is $7$.
So Assertion is incorrect but Reason is correct.

Hence, the correct option is C.

Note:
When weak acids and weak bases are reacted, both the cations and anions undergo hydrolysis reactions. Thus it is difficult to analyze. When a strong base is reacted with a weak acid, then the salt solution will be basic. When a strong acid is reacted with a weak base, then the salt solution will be acidic.