Find the odd-one out ?

Find odd in the following

Three of the following four words are alike in a certain way and one is different. Select the odd word.

Three of the following four letter-clusters are alike in a certain way and one is different. Pick  the odd one out.

Three of the following four numbers are alike in a certain way and one is different. Pick the number that is different form the rest.

Three of the following four letter-clusters are alike in a certain way and one is different. Pick the odd one out.

Three of the following four word pairs are alike in a certain way and one is different. Pick the odd word out.

Three of the following four words are alike in a certain way and one is different. Pick the odd word out.