Which of the following are examples of the null set

$\{ y:y$ is a point common to any two parallellines $\} $

In the following state whether $A=B$ or not :

$A=\{4,8,12,16\} ; B=\{8,4,16,18\}$

Set $A$ has $m$ elements and Set $B$ has $n$ elements. If the total number of subsets of $A$ is $112$ more than the total number of subsets of $B$, then the value of $m \times n$ is

Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:

$\{ x:x$ is a circlein the plane $\}  \ldots \{ x:x$ is a circle in thesame plane with radius $1$ unit $\} $

Examine whether the following statements are true or false :

$\{ a,e\}  \subset \{ x:x$ is a vowelin the English alphabet $\} $