Use the particle theory to describe each of the three states of matter. (MIDDLE SCHOOL) not highschool lol

The answer for #3 is c but i don't know why

Ill give brainiestif one neutron initiates a fission event that produces two neutrons in the products, how many new reactions can now be initiated? if each of the neutrons produced in the first fission event then initiates a fission event that produces one neutron in the products, how many new reactions can now be initiated by each neutron? how many neutrons in total were produced by the two fission events described?

How does the motion of particles in a gas change as the gas cools