Which of the following statements is a contingency?

Statement $1: ~(p\leftrightarrow ~q)$ is equivalent to $p\leftrightarrow q$.

Statement $2: ~(p\leftrightarrow ~q)$ is a tautology.

The dual of the statement $~(p\vee q)\wedge \left[p\vee ~(q\wedge ~r)\right]$ is

Consider the following statements:

$P$: Suman is brilliant

$Q$: Suman is rich

$R$: Suman is honest.

The negation of the statement "Suman is brilliant and dishonest iff Suman is rich" can be expressed as

Simplified form of the switching circuit given below is