Find the missing number?

Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it.

a_c_abb_a_bc_bc_ab 

In each of the following questions. Select the related letter/ word/ number from the given alternatives.

WRITE : XSJUF : : OPEAC : ?

In a certain code language, " ARRAY " is written as "19917". How is " LEARNING " written in that code language?

Choose the correct option from the following options.
9 : 101 ∷ 10 :?

A series is given, with one term missing choose the correct alternative from the given ones that will complete the series.
1, 9, 25, 81, 329,  ? 

Anand is son of Prema . Rajeev is brother of Prema . Neha is daughter of Rashmi . Neha is sister of Rajeev . How is Anand related to Rashmi ?

Direction: Select the related word from the given alternatives.

Carpenter : Saw ∷ Tailor : ?