Verbal Reasoning - Mental Ability Questions

A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
ZXV , USQ , PNL , ?

BACTERIA : ILLNESS :: ____ : ____

If FRIEND is coded as HTKGPF then REVEAL will be coded as:

Akhil is the maternal uncle of Rashmi. Rashmi is the daughter of Ramesh. How is Ramesh related to Akhil?

Find the missing number?

If FRISKED is coded as HTKUMGF, then how will SUN be coded as?

In a certain code language, 'x' represents '+', '÷' represents 'x', '-' represents '÷' and '+' represents '-'. Find out the answer to the following question.

18 x 12 ÷ 5 - 10 + 10 = ?

Find the odd word/letters/number pair from the given alternatives.
(A) Violin
(B) Piano
(C) Flute
(D) Harmonium