Question

1. as the mass of the nucleus increases, what happens to the ratio of neutrons to protons in stable isotopes?

the neutron:proton ratio decreases.
the neutron:proton ratio increases.
the neutron:proton ratio remains 1:1.
the neutron:proton ratio remains 1.5:1.

Explanation:

For light - weight stable isotopes (e.g., \(^{12}\text{C}\) with \(n:p = 1:1\)), as the mass of the nucleus increases (e.g., heavier elements like \(^{238}\text{U}\)), the electrostatic repulsion between protons increases. Neutrons provide additional strong - force binding (without adding electrostatic repulsion) to stabilize the nucleus. So, more neutrons are needed relative to protons.

Answer:

The neutron:proton ratio increases.