Choose the correct alternative for the missing terms in the series: $Y, W, U, S, Q, ?, ?$

Find out the wrong term from the given series.
$1, 2, 6, 15, 31, 56, 91$

Study the following arrangement carefully and answer the question given below:
$R, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, D, 9, U, 2, Y, V$
How many such numbers are there in the above arrangement,each of which is immediately preceded by a consonant but not immediately followed by a consonant?

Choose the correct alternative for the missing term.
$JE, LH, OL, SQ, ?$

Choose the correct alternative to complete the series: $....abb....bb....a....bbab....ba$

Which term will replace the question mark in the series:
$ABD, DGK, HMS, MTB, SBL, ?$