4.0 x 107 NC-1
8.0 x 109 NC-1
8.O x 10-12 NC-1
4.0 x 109 NC-1
Correct answer is D
The electric force experienced in an electric field of intensity E is given by:
F = qE: where q = the test charge.
E = F/Q = 0.4/10-10 = 0.4 X 10-10
= 4.0 X 109 NC-1