Solution:
Ass is the only beast of burden in the group.

Solution:
All except Mathura are cities situated on the banks of Ganga river.

Solution:
In all other pairs, first is the material used to make the second.

Solution:
All except Sarnath are famous battlefields.

Solution:
All except Lizard are aquatic animals.

Solution:
All other groups contain two consecutive vowels of the English alphabet.

Solution:
All except SAARC are world organisations.