Choose the correct alternative answer

$a...bbbc...aab....cca....bbcc$

Choose the correct alternative answer

$bca.....b....aabc....a...caa$

Fill in the blank space for the given series with the correct alternative.
Which term of the series $5, 10, 20, 40, \ldots$ is $1280$?

The following question is based on the five three-digit numbers given below:
$519, 368, 437, 246, 175$
Which of the following is the sum of the middle digits of the highest and the lowest numbers?

Study the following arrangement carefully and answer the question.
$O, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, S, 9, U, 2, Y, X$
Four of the following five are alike in a certain way based on their positions in the above arrangement and so form a group. Which is the one that does not belong to this group?

Find out the wrong term from the given series.
$1, 3, 10, 21, 64, 129, 256, 778$