The sentence,"What is your name?" is

When does the current flow through the following circuit?

Let $p, q$ and $r$ be the statements:
$p$: $X$ is an equilateral triangle
$q$: $X$ is an isosceles triangle
$r: q \vee \sim p$
Then the equivalent statement of $r$ is:

The contrapositive of the statement,"If the side of a square doubles,then its area increases four times",is

The statement $[(p \wedge q)$ $\rightarrow p]$ $\rightarrow (q \wedge \sim q)$ is

Negation of the statement $\forall x \in \mathbb{R}, x^2+1=0$ is