Given below are two statements: 

Assertion (A):  For measuring the resistance of an ionic solution an AC source is used.
Reason (R): Concentration of ionic solution will change if DC source is used.

 

1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.

Hint: The concentration of the ionic solution will change if a DC source is used. 
The concentration of ionic solution changes on using DC current as a source of energy while on passing AC current
concentration does not change. Hence, an AC source is used for measuring resistance. Hence, both assertion and reason are
true and the reason is the correct explanation of assertion.