How many such pairs of letters are there in the word $DOCUMENTARY$,each of which has as many letters between them in the word as there are between them in the English alphabet?

If it is possible to make only one meaningful word from the second,the fourth,the fifth,the seventh and the eleventh letters of the word $DISTRIBUTION$,the third letter of that word is your answer. If more than one such word can be formed,your answer is $M$,and if no such word can be formed,your answer is $X$.

Number of letters skipped in between adjacent letters in the series increases by one. Which of the following series observes the rule given above?

Each of the following questions is based on the following alphabet series.
$A, B, C, D, E, F, G, H, I, J, K, L, M$
$N, O, P, Q, R, S, T, U, V, W, X, Y, Z$
Which letter is the seventh to the right of the thirteenth letter from your left?

If the first three letters of the word $COMPREHENSION$ are reversed,then the last three letters are added and then the remaining letters are reversed and added,then which letter will be exactly in the middle?

Each of the following questions is based on the following alphabet series.
$A, B, C, D, E, F, G, H, I, J, K, L, M$
$N, O, P, Q, R, S, T, U, V, W, X, Y, Z$
If every even letter beginning from $B$ is replaced by an odd number beginning with $3$,which letter/number will be the third to the right of the tenth number/letter counting from your right?