Contrapositive of the statement “If two numbers are not equal, then their squares are not equals” is

Let $F_{1}(A, B, C)=(A \wedge \sim B) \vee[\sim C \wedge(A \vee B)] \vee \sim A$ and $F _{2}( A , B )=( A \vee B ) \vee( B \rightarrow \sim A )$ be two logical expressions. Then ...... .

Which of the following statement is a tautology?

$\sim (p \vee (\sim q))$ is equal to .......

$\left( { \sim \left( {p \vee q} \right)} \right) \vee \left( { \sim p \wedge q} \right)$ is logically equivalent to 

Let $\Delta \in\{\wedge, \vee, \Rightarrow, \Leftrightarrow\}$ be such that $(p \wedge q) \Delta((p \vee q) \Rightarrow q)$ is a tautology. Then $\Delta$ is equal to