Question Analysis: Assertion (A) and Reason (R) type question.

Step 1 (Governing Principle): [0.25 Mark]
The acidity of phenols is determined by the stability of the phenoxide ion formed after the loss of a proton ($H^+$). Electron-Withdrawing Groups (EWG) stabilize the phenoxide ion (increasing acidity), while Electron-Donating Groups (EDG) destabilize the phenoxide ion (decreasing acidity).

Step 2 (Step-by-Step Analysis): [0.5 Mark]

• p-nitrophenol: The nitro group ($-NO_2$) exerts a strong $-I$ and $-M$ effect, which are electron-withdrawing. This stabilizes the negative charge on the phenoxide ion, making it a stronger acid.
• p-methoxyphenol: The methoxy group ($-OCH_3$) exerts a $+M$ effect (electron-donating) despite its $-I$ effect. The $+M$ effect dominates, destabilizing the phenoxide ion, making it a weaker acid.

Step 3 (Final Concluded Answer): [0.25 Mark]
Assertion (A) is False, but Reason (R) is True. In the CBSE marking scheme, this corresponds to the option: (d) Assertion (A) is false but Reason (R) is true.

💡 EL10 Concept Insight: Think of the phenoxide ion as a "hot potato" (the negative charge). The nitro group acts like a cooling fan that takes the heat away (stabilizing it), while the methoxy group acts like a heater that adds more heat (destabilizing it), making the nitro-compound much more comfortable and stable.