Verbal Reasoning - Mental Ability Questions

In a family, there are six members A, B, C, D, E and F. 

A and B are a married couple, A being the male member. D is the only son of C, who is the brother of A. E is the sister of D. B is the daughter-in-law of F, whose husband has died. How is F related to C ? 

In the following question, select the related word pair from the given alternatives.

Book : Pages : : ? : ?

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

18 : 30 : : 36 : ?

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

5 : 30 :: 7 : ?

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

GIKM: RTVX :: HJLN : ?

Select the related word from the given alternatives.

Yellow : Lemon :: Purple : ?

The following equation is incorrect. Which two signs should be interchanged to correct the equation?

16 ÷ 6 + 35 x 9 - 15 = 31

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

BDFH : YWUS :: JLNP : ?