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

$\varnothing \subset A$

In the following state whether $\mathrm{A = B}$ or not :

$A = \{ 2,4,6,8,10\} ;B = \{ x:x$ is positiveeven integer and $x\, \le \,10\} $

If $A$ and $B$ are any two non empty sets and $A$ is proper subset of $B$. If $n(A) = 4$, then minimum possible value of $n(A \Delta B)$ is (where $\Delta$ denotes symmetric difference of set $A$ and set $B$)

Which of the following are sets ? Justify your answer.

The collection of all natural numbers less than $100 .$

Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:

$\{ 2,3,4\}  \ldots \{ 1,2,3,4,5\} $