Verbal Reasoning - Mental Ability Questions

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

5 : 124 :: 7 : ?

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

GH : 78 : : ? : 1819

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

12 : 39 :: 15 : ?

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

Antique : Old : : Weak : ?

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

2 : 10 : : 3 : ?

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

AEIM:BFJN::CGKO:?

Pointing to an old man, Kailash said, "His son is my son's uncle." How is the old man related to Kailash ? 

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

BIRD : AEROPLANE :: FISH : ?