Verbal Reasoning - Mental Ability Questions

In the following question, select the missing number from the given series.
19, 38, ?, 228, 684, 1368

A word is represented by only one set of numbers as given in any one of the alternatives. The sets of numbers given in the alternatives are represented by two classes of alphabets as shown in the given two matrices. The columns and rows of Matrix-I are numbered from 0 to 4 and that of Matrix-II are numbered from 5 to 9. A letter from these matrices can be represented first  by its row and next by its column ,for example 'H' can be represented by 32,41 etc and 'N' can be represented by 98,85 etc. similarly,you have to identify the set for the word ''IOTA''.

If 4 x 9 x 3 = 4 and 5 x 3 x 1 = 3, then
9 x 9 x 7 = ?

In the following question, select the related number pair from the given alternatives.
534 : 2 : : ? : ?

A boy travels 4 km towards south and then takes a right turn travels another 3 km in that direction. How far and in which direction is he now from his original position?

A travels 12 km towards north and then takes a left turn and covers another 5 km. From there, he turns 180° anticlockwise and travels 10 km further. What is the minimum distance between his initial and final position?

In the following question, select the related letters from the given alternatives.
FS : LY : : IV : ?

If in a certain language TEACHER is coded as QBXZEBO, then how is STUDENT coded in the same language?