Which of the following sets are finite or infinite.

The set of positive integers greater than $100$

How many elements has $P(A),$ if $A=\varnothing ?$

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

$\{ x:x$ is a student of class $\mathrm{XI}$ of your school $\}  \ldots \{ x:x$ student of your school $\} $

Let $A, B$ and $C$ be three sets. If $A \in B$ and $B \subset C$, is it true that $A$ $\subset$ $C$ ?. If not, give an example.

List all the elements of the following sers :

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