Write down all the subsets of the following sets :
(i) {a}
(b) {a, b}
(c) `{1,2,3}`
(d) `phi`

Explanation

(i) Number of subsets of set `{a} = 2^(1) = 2` Subsets of `{a} = phi, {a}`
(ii) Number of subsets of set `{a,b} = 2^(2)=4`. Subsets of set {a,b} are `phi, {a},{b},{a,b}`
(iii) Number of subsets of set `{1,2,3} =2^(3)=8` Subsets of set `{1,2,3}` are
`= phi, {1},{2},{3},{1,2},{2,3},{3,1},{1,2,3}`
(iv) Number of subsets of set `phi = 2^(0)=1` which is `phi` itself
Therefore, subsets of set `phi = phi`.