If a stable neutral atom has a mass number of 31, the number of electrons and neutrons respectively are

To answer this question, let's break it down step by step:

Mass Number: The mass number is the total number of protons and neutrons in an atom's nucleus. In this case, the mass number is given as 31.

Stable Neutral Atom: A stable neutral atom has no overall electrical charge, meaning the number of protons (positively charged) must equal the number of electrons (negatively charged).

If we symbolize the number of protons by the atomic number (Z), we can say:

1. **Protons = Electrons** in a neutral atom.

2. **Mass Number (A) = Protons + Neutrons**.

Given that the mass number is 31, we have the equation:

A = Protons + Neutrons = 31.

Assuming a commonly known stable element like Phosphorus, which has an atomic number (Z) of 15, it means:

1. **Protons = 15**.

2. **Electrons = 15** (because it's a neutral atom).

3. To find Neutrons: Neutrons = Mass Number - Protons = 31 - 15 = 16.

So, in this scenario, the number of electrons is 15 and the number of neutrons is 16. This combination is found in the first option given.