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

$\{ 3,4\}  \in A$

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 $C$

$\varnothing$

Write down all the subsets of the following sets

$\{ 1,2,3\} $

State which of the following sets are finite or infinite :

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

Write the following sets in roster form :

$D = \{ x:x$ is a prime number which is divisor of $60\} $