Study the following arrangement carefully and answer the questions given below:
$R, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, D, 9, U, 2, Y, V$
If all the numbers in the above arrangement are dropped,which of the following will be the ninth to the left of $D$?

Two terms have been put within brackets. Mark your answer as:
$4, 7, (9), 10, 13, 15, (16), 19$

Choose the correct alternative to complete the series: $....a...b...abaa...bab...abb$

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?

What should come next in the following letter series?
$nsi, org, pqe, qpc, ?$

Fill in the blank space for the given series with the correct alternative.
$8, 24, 12, 36, 18, 54, (\ldots)$