Assertion : p -Methoxyphenol is a weaker acid than m...

The $-OCH_3$ group exerts a $-I$ effect and a $+R$ effect.

In $p$-methoxyphenol, the $+R$ effect of the $-OCH_3$ group is dominant over its $-I$ effect. This increases the electron density on the phenoxide ion, destabilizing the conjugate base and making it a weaker acid.

In $m$-methoxyphenol, the $+R$ effect does not operate at the meta position. Only the $-I$ effect operates, which stabilizes the phenoxide ion, making it a stronger acid.

Thus, $p$-methoxyphenol is a weaker acid than $m$-methoxyphenol. The Assertion is true.

The Reason states that the $-OCH_3$ group exerts a $+I$ effect, which is incorrect since oxygen is more electronegative than carbon and exerts a $-I$ effect. Therefore, the Reason is false.

Answer: Assertion is true but Reason is false.