Which of the following will come in place of the question mark (?) in the following letter-number series?

$M3V,O5U,R7T,T9S,W11R,?$

Which of the following will come in place of the question mark (?) in the following letter-number series?

$B6D, C12I, D20P?$

What will come in place of question mark (?) in the following series?

$X5C, U8F, ?, O17L, L23O$

What should come in place of the question mark (?) in the following series?

$C0G, E2I, ?, I12M$

Which of the following will come in place of the question mark (?) in the following letter-number series?

$C1A, F4E, H9I, ?, M25U$

What will come in place of the question mark (?) in the following series?

$A7H, C14H, F5K, J25Q, O50T, ?, B25I$

What will come in place of question mark (?) in the following series?

$X2L, T6L, ?, O20I, N30F, N42B$

$1799, ?, 59, 14, 4, 1.5$

In the following question, a sequence of groups of letters and numbers is given with terms missing as shown by the question mark (?). Choose the missing term out of the given alternatives.

$D-4, F-6, H-8, J-10, ?, ?$