Cardinality of Power Set of a Set

Q.

What is universal and power set?

Q. For any empty set $X,$ the value of $n\left(P\right(P\left(P\right(P\left(P\right(X\left)\right)\left)\right)\left)\right)=$

1. $2^4$
2. $2^5$
3. $2^6$

Q. The relation on the set $A=\{x:1<|x|\le 4,x\in Z\}$ is defined by $R=\left\{\right(x,y):y=|x|\}.$ Then the number of elements in the power set of $R$ is

1. $16$
2. $32$
3. $64$
4. $128$

Q. If $A=\{x:x$ is a prime number between $2$ and $16\},$ then number of subsets of $A$ with exactly two elements is

1. $5$
2. $10$
3. $15$
4. $20$