Write down all the subsets of the following sets

$\{ a,b\} $

State which of the following sets are finite or infinite :

$\{ x:x \in N$ and $x$ is prime $\} $

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

$1 \subset A$

Write down all the subsets of the following sets

$\{ a\} $

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

The set of lines which are parallel to the $x\,-$ axis

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 $A \in B,$ then $x \in B$