Five Styrofoam balls are suspended from insulating threads. Several experiments are performed on the balls and the following observations are made:
(i) Ball A repels C and attracts B.
(ii) Ball D attracts B and has no effect on E.
(iii) A negatively charged rod attracts both A and E.
An electrically neutral Styrofoam ball gets attracted if placed nearby a charged body due to induced charge. What are the charges, if any, on each ball A,B,C,D, and E?

Options

A. A = +, B = -, C = +, D = 0, E = +
B. A = +, B = -, C = +, D = +, E = 0
C. A = +, B = -, C = +, D = 0, E = 0
D. A = -, B = +, C = -, D = 0, E = 0

Answer

C

Explanation

From (i), As A repels C, so both A and C must be charged similarly. Either both are +ve or both are -ve. As A aslo attract B, so charge on B should be opposite of A or B may be uncharged conductor.
From (ii) As D has no effect on E, so both D and E should be uncharged, and as B attracts uncharged D, so must be charged and D must be on uncharged conductor.
From (iii) a - ve charged rod attract the charged ball A, so must be +ve, and from exp. (i) C must also be +ve and B must be -ve.