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

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

State which of the following sets are finite or infinite :

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

Write the following intervals in set-builder form :

$\left[ {6,12} \right]$

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

$ 8\, .......\, A $

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

$\{ \{ 3,4\} \}  \subset A$

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 $C$

$\varnothing$