Study the following arrangement carefully and answer the question given below:
$R, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, D, 9, U, 2, Y, V$
Which of the following is exactly in the middle between $A$ and $D$ in the above arrangement?

Find the wrong number in the series.
$10, 26, 74, 218, 654, 1946, 5834$

How many such digits are there in the number $5231698$ each of which is as far away from the beginning of the number as when the digits are rearranged in ascending order?

How many such digits are there in the number $52361984$ each of which is as far away from the beginning of the number as when the digits are rearranged in ascending order within the number?

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 $D$?

Choose the correct alternative to complete the series: $a \_ n \_ b \_ \,, \, \_ n c b \_ \,, \, \_ n c b$