Find out the wrong term from the given series.
$121, 143, 165, 186, 209$

Fill in the blank space for the given series with the correct alternative.
$2, 6, 12, 20, 30, 42, 56, (\dots)$

Find the missing letters for the given series from the given alternatives:
$aab....bbaaa....cbba.....abc.....ba$

Fill in the blank space for the given series with the correct alternative.
$12, 32, 72, 152, (\ldots)$

Find the missing term in the series: $2, 6, 12, 20, 30, ?$

Study the following arrangement carefully and answer the question given below:
$7, R, E, T, 4, A, 9, \%, D, F, 1, U, \#, B, @, 8, H, I, W, M, \star, 3, 2, V, \,5,N,P,6,Q$
How many such numbers are there in the above arrangement,each of which is immediately preceded by a letter but not immediately followed by a symbol?