(i) “Not p” is the negation of the assertion p. The negation of p is represented by $\sim p$. The truth value of $\sim p$ is the opposite of the truth value of p.

The negation of the statement is “Cow does not have four legs”.

(ii) “Not p” is the negation of the assertion p. The negation of p is represented by $\sim p$. The truth value of $\sim p$ is the opposite of the truth value of p.

The negation of the statement is “A leap year does not have 366 days”.