We know that number of subsets of any set is 2n where n is the number of elements in that set.Every non-empty set has two subsets ϕ and the set itself.(i) The subsets of {a} are ϕ and {a}.(ii) The subsets of {a,b} are ϕ,{a},{b},and{a,b}.(iii) The subsets of {1,2,3} are ϕ,{1},{2},{3},{1,2},{2,3},{1,3},and{1,2,3}(iv) The only subset of ϕ is ϕ.