Verbal Reasoning - Mental Ability Questions

Find the next in this series:
YC3, XF6, WI9, ........

If 4 * 2 = 3 and 8 * 4 = 3 , then 21 * 7 = ?

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

Pension, Aptitude, Captain, Tropical, Survive, ?

Which word comes first in the dictionary?

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

D, G, K, N, R, ?, ?, B, F

Shubham's mother is the sister-in-law of Shashi and Shashi is the only daughter of Parmeshwar. Ravi is Shubham's brother. How is Shashi related to Ravi?

In the following question, by using which mathematical operators will the expression become correct?
27 ? 9 ? 18 ? 24 ? 12

Identify the diagram that best represents the relationship among the given classes.
Brain, Cerebrum, Liver, Human body