Find the odd from the given alternatives?

Three of the following four triads are alike in a certain way as they are formed by performing the same mathematical operations among themselves and thus form a group. Which triad does NOT belong to that group?

Find the odd one in the following.

Four number have been given out of which three are alike in some manner, while is different. Choose the odd one.

Directions: In the following question four words have been given, out of which three are alike in some manner and the for one is different. Choose out the odd one.
Triangle
Rectangle
Circle
Square 

Four words have been given of which three are alike in some way and one is different. Choose the odd one out.

In each of the following questions, four numbers are given out of which three are like in some manner while one is different. Choose the one which is different from the rest three?