Choose the correct alternative for the missing term in the series: $CE, GI, KM, OQ, ?$

How many such numbers are there in the following series,each of which is immediately preceded by $6$ but not immediately followed by $4$?
$3, 8, 6, 8, 4, 2, 6, 9, 8, 4, 6, 8, 4, 8, 6, 2, 6, 8, 4, 8$

Two terms have been put within brackets in the following series. Mark your answer based on the correctness of these terms:
$2, 5, (12), 25, 41, 61$

Study carefully the following arrangement of letters, digits and symbols to answer these

questions.

$M, 7 ,\&, 8, L ,P ,@ ,Q ,N ,\beta ,T ,Y ,3 ,2 ,= ,E ,\$ ,4 ,9 ,\#, G ,H ,5$

If all the symbols are deleted from the arrangement, which of the following will be fourth to the left of the $17^{th}$ element from the left end ?

Fill in the blank space for the given series with the correct alternative.
$1, 1, 3, 9, 6, 36, 10, 100, (\ldots), 225$

Find out the missing term for the given series from the given alternatives:
$AZ, BY, CX, ?$