In the series 2, 6, 18, 54, ...... what will be the 8th term ?

Answer: Option B

Clearly, 2 x 3 = 6, 6 x 3 = 18, 18 x 3 = 54,.....
So, the series is a G.P. in which a = 2, r = 3.
Therefore 8th term = ar^8-1 = ar⁷ = 2 x 3⁷ = (2 x 2187) = 4374.