How many pairs of letters are there in the word "$BUCKET$" which have as many letters between them in the word as in the alphabet?

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 the above alphabet is written in the reverse order,which letter will be the twelfth to the left of the sixteenth letter from your left?

Find which one word cannot be made from the letters of the given word: $RECOMMENDATION$.

If it is possible to make a meaningful word with the fourth,the seventh,the eleventh and the thirteenth letters of the word $CATEGORISATION$,which of the following will be the first letter of that word? If no such word can be made,give $X$ as the answer. If more than one such word can be made,give $M$ as the answer.

Find which one word cannot be made from the letters of the given word.
$CHROMATOGRAPHIC$

$A$ group of letters is given which are numbered $1, 2, 3, 4, 5$ and $6$. Below are given four alternatives containing combinations of these numbers. Select that combination of numbers so that the letters arranged accordingly form a meaningful word.
$E, O, C, D, L, I$
$1, 2, 3, 4, 5, 6$