Numbers Q6

6.The smallest value of n, for which  2n + 1 is not a prime number, is:

[A] 3

[B] 4

[C] 5

[D] None of these

Answer : [B]

Explanation :

(2 x 1 + 1) = 3, (2 x 2 + 1) = 5, (2 x 3 + 1) = 7. (2 x 4 + 1) = 9. which is not prime.

n = 4.