Let $A=\{1,2,3,4,5,6\} .$ Insert the appropriate symbol $\in$ or $\notin$ in the blank spaces:

$ 5\, .......\, A$

$A = \{ x:x \ne x\} $ represents

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

$\varnothing \subset A$

Which of the following are sets ? Justify your answer.

The collection of all natural numbers less than $100 .$

State which of the following sets are finite or infinite :

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

List all the elements of the following sers :

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