State which of the following sets are finite or infinite :

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

Write down all the subsets of the following sets

$\emptyset $

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

The set of numbers which are multiple of $5$

Write down all the subsets of the following sets

$\{ a\} $

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

$ 0\, ........\, A $

Which of the following are sets ? Justify your answer.

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