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 $B$)

Examine whether the following statements are true or false :

$\{ a\}  \in \{ a,b,c\} $

Write the following as intervals :

 $\{ x:x \in R, - 4\, < \,x\, \le \,6\} $

$A = \{ x:x \ne x\} $ represents

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

$ 2 \, ....... \, A $

How many elements has $P(A),$ if $A=\varnothing ?$