Verbal Reasoning - Mental Ability Questions

Select the related letters from the given alternatives.

ACE : YAC :: BDF : ?

Select the related word/letters/number from the given alternatives.

GLIDERS : ERSDGLI : : TOASTER : ?

Choose the related word/letters/number from the given alternatives.

Seismology : Earthquake :: Hydrology : ?

Select the related word/letters/number from the given alternatives.

Agra : Yamuna : : Varanasi : ?

Select the related letters from the given alternatives.

GIK : PRT :: DFH : ?

Select the related word/letters/number from the given alternatives.

FUNGI: MYCOLOGY:: TISSUE: ??

Select the related word/letters/number from the given alternatives.

IJKL: PQRS : : EFGH : ?

If 20 - 10 means 200, 8 / 4 means 12, 6x2 means 4, then

100 - 10 x 1000/ 1000 + 100 x 10 = ?