Clearly, A contains four elements, namely `1, {2} , {3,4 } and 5`
(i) `2 in A` is incorrect. The correct statement would be `{2} in A`.
(ii) `{2} sub A ` is incorrect. The correct statement is ` {{2}} sub A`.
(iii) Clearly, `2 lin A ` and therefore , ` {1, 2 } sub A` is correct. THe correct statement would be `{1,{2},} sub A`.
(iv) Clearly, `{3,4}` is an element of A. So, ` {3,4}, sub A` is incorrect and ` {{ 3,4}} sub A ` is correct.
(v) Since 1 and 5 are both elements of A, so `{1,5} sub A` is correct.
(vi) Since ` phi lin A`, so `{phi} sub A` is incorrect while `phi sub A ` is correct.
(vii) Since ` 1 in A`, so ` 1 sub A` in incorrect and therefore , `{1} sub A ` is correct.
(viii) Since ` 2 lin A and 3 lin A` , so `{1,2,3,4}sub A ` is incorrect. The correct statement would be `{1,{2}, {3,4}}sub A`.