What is the role of neutrons in an atom? a) neutrons provide a negative charge to the atomic nucleus b) neutron keep protons apart so they don’t repel each other c) neutrons neutralize electrons d) neutrons provide a positive charge to the atomic nucleus

B) neutron keep protons apart so they don’t repel  each other

Explanation:

Neutrons are of almost same mass as that of protons mass or we can say it is slightly greater than the mass of proton

There is no charge on the neutrons as they are neutral and they resides inside the nucleus.

since nucleus is a small region where large number of protons and neutrons exists so in this small region protons must have large repulsion force between them but since this repulsion force is counterbalanced by the strong nuclear force between the neutrons and protons so here role of neutrons is to provide sufficient strong force to bound the nucleons together

so here correct answer will be

B) neutron keep protons apart so they don’t repel  each other

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.