(i) False
A={2,3,4,5} B={3,6}
⇒A∩B={3}
So, A and B are not disjoint sets.
(ii) False
A={a,e,i,o,u} , B={a,b,c,d}
A∩B={a}
Hence, A and B are not disjoint sets.
(iii) True
A={2,6,10,14} ,B={3,7,11,15}
A∩B=ϕ
Hence, A and B are disjoint sets.
(iv) True
A={2,6,10} ,B={3,7,11}
A∩B=ϕ
Hence, A and B are disjoint sets.