List of top Logical Reasoning Questions on Sequence asked in ATMA

Which is the missing letter in the series given below?
C, E, H,__, Q, W

Find the missing term:
8:28::27:?

Find the missing term:
BEGK:ADFJ::PSVY:?

Find the missing term:
QAR, RAS, SAT, TAU, _____

Find the missing term:
B2CD, _____, BCD4, B5CD, BC6D