Verbal Reasoning - Mental Ability Questions

From the given alternative words, select the word which can be formed using the letters of the given word:

COMMUNICATION

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

xy_kx_zk_yzk xyz_ _

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.
1, 5, 30, 210, 1680, ?

If (2)#* 4 = 2 and (4)#* 4 = 16, then what is the value of A in (6)#* A = 18?

Looking at a lady, Joey said, "She is the mother of my mother's mother-in-law's husband". How is the lady related to Joey's father?

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

-7/4, -1, -0.25, ? , 5/4, 2

In the following figure, rectangle represents Doctors, circle represents Essayists, triangle represents cooks and square represents Europeans. Which set of letters represents Essayists who are not cooks?