Which of the following are sets ? Justify your answer.

A collection of novels written by the writer Munshi Prem Chand.

Consider the sets

$\phi, A=\{1,3\}, B=\{1,5,9\}, C=\{1,3,5,7,9\}$

Insert the symbol $\subset$ or $ \not\subset $ between each of the following pair of sets:

$\phi \,....\,B$

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

$ 2 \, ....... \, A $

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

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

The set of circles passing through the origin $(0,0)$

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

$\{\varnothing\} \subset A$