Which of the following numbers will replace the question mark (?) in the given series?

$\left[\frac{1}{176}\right],\left[\frac{1}{88}\right], ?,\left[\frac{1}{22}\right],\left[\frac{1}{11}\right]$

Select the number from among the given options that can replace the question mark (?) in the following series.

2, 6, 9, 27, 30, 90, ?

Select the set in which the numbers are related in the same way as are the numbers of the given sets.

(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding / Subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is NOT allowed)

(15, 23, 31)

(33, 41, 49)

The second number in the given number-pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) is/are followed in all the number-pairs, except one. Find that odd number-pair.