Solution:
Discernment ,Perception and Penetration are in meaning.

Solution:
83 is the only prime number in the group.

Solution:
This is the only group containing three vowels.

Solution:
In all other pairs, second number is 6 times the first.

Solution:
All except Chicken can live in water.

Solution:
In all other groups, there is a gap of two letters between the second and third as well as between the fourth and fifth letters.

Solution:
Mercury is the only liquid metal in the group.