Question

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

Answer 1

We know that if A is a set with m elements i.e., n(A) = m, then n[P(A)] = 2^m. 

If A = Φ, then n(A) = 0. 

∴ n[P(A)] = 20 = 1 

Hence, P(A) has one element.