Verbal Reasoning - Mental Ability Questions

In the following question, from the given alternative words, select the word which cannot be formed using the letters of the given word.
Biological

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
a _ bc _ a _ bcdabc _ da _ cd _

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

2, 3, 7, 16, ?

Which of the following diagram represents the relationship among Tall men, Black haired, Indians?

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

From the given words, select the word which can be formed using the letters of the given word.
AMPLIFICATION

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?
25 + 10 ÷ 240 x 16 = ?

Find out the odd word/letters/number/number pair from the given alternatives.