Which Indian city hosted the sixth India-Singapore

What will come in the place of question mark?

Select the option in which the pair of letter clusters is related in the same way as the pair of letter clusters given below.

GPU: KTY 

Select the option that is related to the third number in the same way as the second number is related to the first number.

223 : 350 :: 519 : ?

Select the option that is related to third letter cluster in the same way second letter cluster is related to first letter cluster.

Fish : Aquarium ::  Birds : ? 

Select the option that is related to the third term in the same way as the second term is related to the first term.

Bhubaneswar : Odisha :: Aizawl : ?

Choose the word which is different from the rest