Orthocenter of an right angle triangle lies on

In the following question, select the odd pair of numbers from the given alternatives.

Four letter-clusters have been given, out of which three are alike in a certain way and one is different. Select the letter-cluster that is different.

Find the odd one out from the following options. 

Four number-pairs have been given, out of which three are alike in some manner and one is different. Select the number-pair that is different.

In the following question, select the odd word from the given alternatives.

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

Four of the following five are similar in a certain way, so create a group.

Which of these is not related to this group?

Select the odd letters from the given alternatives?

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

Select the word which does not belong to the same group from the given alternatives.