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

Let $A = \{1, 2, \{3, 4\}, 5\}$. Is the statement $\{3, 4\} \in A$ correct or incorrect? Explain.

Examine whether the following statement is true or false:
$\{x : x \text{ is an even natural number less than } 6\} \subset \{x : x \text{ is a natural number which divides } 36\}$

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 a universal set for all the three sets $A$,$B$ and $C$?
$X = \{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10\}$

Which of the following are sets? Justify your answer.
$A$ collection of the most dangerous animals of the world.

Is it true that for any sets $A$ and $B$,$P(A) \cup P(B) = P(A \cup B)$? Justify your answer.