Complete: ACEG : IKMO :: QSUW : ?

In the series of letters given below, which option will come in the place of question mark (?)? BXF, DVI, FTL, HRO, ?

Which letter should replace A, D, G, J, M, ?

Choose the group of letters which is different from others.

In English alphabet, which is the 17th letter from your left?

In a code language, if GREAT is written as 718222620 and MONK is written as 13121411, then how will VIGOROUS be written in the same language?