How many such pairs of letters are there in the word 'DISCOVER' each of which has as many letters between them in the word (in both forward and backward direction) as they have between them in English alphabetical series:

How many such pairs of letters are there in the word ‘JACUZZIS’ each of which has as many letters between them in the word as in the English alphabetical series?

If the $2\mathrm{nd}, 7\mathrm{th} \mathrm{and} 8\mathrm{th}$, letters of the word ‘Mailings’ are used to make a word, determine the middle letter of that word. If more than one words is possible, mark X as the answer. If no word is possible, mark Z as the answer.

How many pairs of letters are there in the word 'BACKBLOCKS' which has as many letters between them in the word as in the alphabet in both directions ?

The letters in the word ‘MORTIFY’ are changed in such a way that the vowels are replaced by the previous letter in the English alphabet and the consonants are replaced by the next letter in the English alphabet. Which of the following will be the fourth letter from the right end of the new set of letters?