Ionic compounds is your answer. What happens is one atom donates electron(s) to the other atom, making one positive and the other negative. The opposite atoms attract, forming an ionic bond.
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I'm not sure, I think it's option A.
Let me know if I'm wrong!
Answer:

Explanation:
Let the sphere is uniformly charge to radius "r" and due to this charged sphere the electric potential on its surface is given as

now we can say that


now electric potential is given as


now work done to bring a small charge from infinite to the surface of this sphere is given as


here we know that

now the total energy of the sphere is given as




backward movement
because momentum = mass × speed
And mass must be in positive value..
so negative value is speed
which moving backward..