Question

Which among the following statement is incorrect

• A. $p\wedge (\sim p)$ is a contradiction
• B. $(p\Rightarrow q)\iff (\sim q\Rightarrow \sim p)$ is a contradiction
• C. $\sim (\sim p)\iff p$ is a tautology
• D. $p\vee (\sim p)$ is a tautology

Answer 1

The correct option is B $(p\Rightarrow q)\iff (\sim q\Rightarrow \sim p)$ is a contradiction

$p\Rightarrow q$ is logically equivalent to $\sim q\Rightarrow \sim p$
$\therefore (p\Rightarrow q)\iff (\sim q\Rightarrow \sim p)$ is a tautology and not a contradiction.

So it is the only incorrect statement among all the given statements.