Question

what is the mass number?

Explanation:

Step1: Determine the number of protons and neutrons

Protons and neutrons contribute to the mass number. From the diagram, there is 1 proton (red) and 1 neutron (gray).

Step2: Calculate the mass number

Mass number = number of protons + number of neutrons. So, mass number = \(1 + 1\).

Answer:

\(2\)