How many elements has P(A), if `A =varphi`?

Explanation

`:. A = phi rArr n(A) = 0`
`n{P(A)} = 2^(n(A)) = 2^(0) = 1`
`2{P(A)} = 2^(n(A)) = 2^(0) = 1`
So, number of element in `P(A)` is 1.