Field planting season for poplar tree

What should come in place of the question mark (?) in the given series based on the English alphabetical order?

RJK, PMI, NPG, LSE, ?

Select the wrong term in the given alpha-numeric series.

L11, O22, R44, U44, X55

Which two symbols from amongst the given options should be interchanged to make the given equation correct?

Which number will replace the question mark (?) in the following number series?

3, 7, 22, 45, 136, ?, 820

Three of the following number pairs are alike in some manner and hence form a group. Which number pair does NOT belong to that group?

‘F + R’ means ‘F is the mother of R’

‘F – R’ means ‘F is the father of R’

Select the option that can replace the question mark (?) in the following series.

FM61, EK58, DI55, CG52, ?

In a certain code language,

‘M & N’ means ‘M is the wife of N’,

‘M @ N’ means ‘M is the brother of N’,