If a set $A$ has $n$ elements, then the total number of subsets of $A$ is

State whether each of the following set is finite or infinite :

The set of numbers which are multiple of $5$

List all the elements of the following sers :

$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $

State which of the following sets are finite or infinite :

$\{ x:x \in N$ and ${x^2} = 4\} $

Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?

$\varnothing \in A$

In each of the following, determine whether the statement is true or false. If it is true, prove it. If it is false, give an example.

If $x \in A$ and $A \not\subset B$, then $x \in B$