(i) False As 3 ∈ {2, 3, 4, 5}, 3 ∈ {3, 6} ⇒ {2, 3, 4, 5} ∩ {3, 6} = {3}
(ii) False As a ∈ {a, e, i, o, u}, a ∈ {a, b, c, d} ⇒ {a, e, i, o, u } ∩ {a, b, c, d} = {a}
(iii) True As {2, 6, 10, 14} ∩ {3, 7, 11, 15} = Φ
(iv) True As {2, 6, 10} ∩ {3, 7, 11} = Φ