Let R be the relation in the set $\mathbb{N}$ given by $R = \{(a, b) : a = b - 2, b > 6\}$. Which of the following is the correct answer?

If $n(A) = 2$ and the number of relations from set A to set B is $1024$, then $n(B)$ is

If $A = \{1, 2, 3, 4, \ldots, 10\}$, then the number of non-empty subsets of A containing only even number is

If $A = \{a, b, c, d, e, f\}$, then the number of subsets of A which contains at least $2$ elements is