\\\\(\ extbf{Step -1: Number of elements in A.}\\\\) \\\\(\ ext{It is given that }A = \\phi\\\\) \\\\(\ ext{This means that A has 0 elements, hence }n = 0.\\\\)\\\\(\ extbf{Step -2: Number of elements in a power set.}\\\\) \\\\(\ ext{Number of elements in a power set is given by, }\\\\) \\\\(m[P(A)] = 2^n\\\\) \\\\(\ ext{where n is the number of elements in A.}\\\\) \\\\(\ herefore m[P(A)] = 2^0 = 1 \ ext{ element.}\\\\)\\\\(\ extbf{Hence, P(A) contains 1 element.}\\\\)