Fill in the blank space for the given series with the correct alternative.
$21, 25, 33, 49, 81, (...)$

Choose the correct alternative to fill in the blanks in the series: $abca....bcaab....ca....bbc...a$

The following question is based on the five three-digit numbers given:
$513, 248, 371, 634, 167$
Which of the following is the middle digit of the second highest number among these numbers?

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 numbers are deleted from the arrangement, then which of the following will be fifth to the right of the $13^{th}$ element from the right end?

Choose the correct alternative to fill in the blanks in the series: $abb . . . . baa . . . . a . . . bab . . . . aba$

Choose the correct alternative for the missing term in the series: $shg, rif, qie, pkd, ?$