Verbal Reasoning - Mental Ability Questions

In the following question, select the number which can be placed at the sign of question mark(?) from the given alternatives.

A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
dem, fgo, hiq, _______

If the code for MOTHER is JRQKBU then what is the code for PRINCIPAL?

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

PRQ, NPO, LNM, ?, HJI

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

'Car' is related to 'Garage' in the same way as 'Hen' is related to ___.

The weights of 4 boxes are 30, 20, 50 and 90 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes and in a combination a box can be used only once?

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

144, 256, 400, ?