Solution:

Provided that A= {1, 2, {3, 4}, 5}

(i) {1, 2, 5} ∈ A is incorrect

{1, 2, 5} is not an element of A.

(ii) {1, 2, 3} ⊂ A is incorrect

3 ∈ {1, 2, 3}; in which, 3 ∉ A.