Verbal Reasoning - Mental Ability Questions

In the folowing questions pickout the most sutiable substitute for the question mark?

6 : 222 :: 25 : ?

Select the related word/letters/number from the given alternatives.

MANTLE : SFTYRJ :: PARROT : ?

Select the related word/letters/number from the given alternatives.

Gloomy : Dull : : Merciless : ?

Select the related word/letters/number from the given alternatives.

JY : 35 : : RT : ?

Select the related word/letters/numbers from the given alternatives:

Calender : Dates : : Dictionary: ?

What comes next in the series?

B, D, H, N, ?

Select the related word/letters/number from the given alternatives.

1331 : 11:: 13824 : ?

Select the related word from the given alternatives.

Father : Parent :: Sister : ?