Verbal Reasoning - Mental Ability Questions

In the given series one term is missing. Choose the correct alternative from the given ones that will complete the series.

XBC,WFG,VJK,?

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series. GJT, IMR, KPP, MSN, ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.
MHZ, NIW, OKT, PNQ, ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

?, HI, OP, WX

If IRON is written as GOKI, then KNIFE may be written as

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

AK, DQ, GV, JZ, ?

Mathur's uncle's daughter's brother is Salmi. How is Sonm related to Mather? 

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it? a_c_e_b_de