Assertion (A) : Formic acid is a stronger acid than acetic acid. Reason (R) : Formic acid is ah organic acid.

Assertion (A) is true: formic acid (HCOOH) is stronger than acetic acid (CH3COOH). The standard rationale is that the conjugate base of formic acid (formate) is more stable than the acetate ion because the electron-releasing +I effect of the methyl group in acetate concentrates negative charge and destabilizes the conjugate base, making acetic acid less acidic. Both compounds are carboxylic (i.e., organic) acids, so the statement in Reason (R) is factually correct but does not explain why formic acid is stronger — classification as an "organic acid" says nothing about relative acidity. Quantitatively, formic acid has a lower pKa than acetic acid, consistent with greater acidity [1].

Sources

1. [1] https://uomustansiriyah.edu.iq/media/lectures/6/6_2021_09_18!12_47_42_AM.pdf