Analogy Questions

In the following question, select the related letter pair from the given alternatives.PIR : OHQ : : ? : ?

Select the related word from the given alternatives.
Cotton : White :: Coal : ?

In the following question, select the related word from the given alternatives.
Sheep : Lamb : : Cow : ?

In the following question, select the related letters from the given alternatives.
BPTW : CQUX : : CHNS : ?

In the following question, select the related word from the given alternatives.
Mathematics : Formulas : : Chemistry : ?

In the following question, select the related number from the given alternatives.
40 : 100 : : 56 : ?

Select the related word/letters/numbers from the given alternatives: DBCE : QOPR :: JLKI : ?

Select the related number from the given alternatives.
3/7 : 7/3 :: 9/2 : ?