The primary unit of length in the metric system is the:
kilometer
meter
millimeter
centimeter

Meter, everthign else is a power of 10 of it

The correct answer is C. Electrostatic repulsion between the positively charged nucleus and alpha particles. Alpha particles contain positive charges. From the principle of like charge repels like charge, these positively charged alpha particles repelled or failed to collide with the positively charged nucleus; so they bounced back from each other.