Verbal Reasoning - Mental Ability Questions

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?

m_o_mn_p_no_

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

RS, ? , BC, GH

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

Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?

aa_ab_ _aaa _a

A series is given with one term missing. Select the correct alternative from the given ones that will complete the series.

NVX, LTV, JRT, ?, FNP

Select the related word/letters/number from the given alternatives.
PEON : QRHS : : JOCK : ?

Select the related word/letters/number from the given alternatives.
34 : 81 : : 23 : ?

Pointing to a boy in a photograph, Neena said, "He is the son of my grandmother's only daughter". How is Neena related to the boy?