(i) Let A={a}

Now, number of elements in A = 1

Number of subsets of A = 2¹

∴ subsets of A are: ϕ, {a}

(ii) Let A={a, b}

Now, number of elements in A = 2

Number of subsets of A = 2² = 4

∴ subsets of A are: ϕ, {a}, {b}, {a, b}

(iii) Let A={1, 2, 3}

Now, number of elements in A = 3

Number of subsets of A = 2³ = 8

∴ subsets of A are:

ϕ, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}

(iv) Let A=ϕ

Now, number of elements in A = 0

Number of subsets of A = 2⁰ = 1

∴ subset of A is: ϕ