Assume the charge initially on spheres A and B is . After sphere C is touched to sphere A, the charges on sphere A is , the charge on sphere B is , and the charge on sphere C is . After sphere C is touched to sphere B, the charge on sphere A is , the charge on sphere B is and the charge on sphere C is . The force between spheres A and B is given by Coulomb's law
So, the initial force is and the final force is Therefore, answer (D) is correct. |

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