Which of the following are sets ? Justify your answer.

The collection of all boys in your class.

Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$

$\{0,1,2,3,4,5,6,7,8,9,10\}$

Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$

$\{ 1,2,3,4,5,6,7,8\} $

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

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

Write the following intervals in set-builder form :

$\left( { - 3,0} \right)$

State which of the following sets are finite or infinite :

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