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.

? , 9, 19, 39, 79

Prem starts to school from his house and walks 400 metres towards north, turns left and walks 100 metres, turns left and walks 200 metres, turns left and walks 100 metres. How far he is away from his house?

Vineet travels 16 km towards west, turns right and travels another 12 km, and then takes two successive left turns covering 8 km and 12 km in each turn respectively. Finally, he takes a right turn and travels 10km further. How far is he now from his original position ?

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

If ' + ' means minus , ' - ' means multiplication , ' ÷ ' means plus , and ' x ' means division , then 15 - 3 + 10 x 5 ÷ 5

In each question below are three statements followed by two conclusions numbered I and II. You have to take the three given statements to be true even if they seem to be at variance with commonly known facts and then decide which of the given conclusions logically follows from the three statements disregarding commonly known facts.
Statements:
All numbers are digits.
All alphabets are numbers.
All words are alphabets.
Conclusions:
I. All words are digits.
II. Some numbers are not words.

Select the related word from the given alternatives.
River : Stream :: Ocean : ?

Select the related word/letters/number from the given alternatives.
DI : M : : CR : ?