JEE Main · 2021 · 17 Mar 2021 · Shift 1 · Mathematical Reasoning *

The biconditional is a tautology exactly when its two sides are logically equivalent, so $q\ast (\sim p)$ must be equivalent to $p\Rightarrow q$, that is to $(\sim p)\vee q$. Hence $\ast$ is the disjunction $\vee$. Then

and a disjunction $(\sim q)\vee p$ is the implication $q\Rightarrow p$.