Which statement correctly describes a proton?

• A. Mass approximately 1 amu
• B. Negative charge
• C. Located outside the nucleus
• D. Mass approximately 2 amu

Answer: (A)

Protons are positively charged subatomic particles that reside in the atomic nucleus and contribute most of the atom’s mass. Their mass is about 1 atomic mass unit (amu), which is roughly the same as a neutron and far larger than the electron’s mass. The positive charge of a proton is denoted as +e, not negative. Protons stay in the nucleus; electrons orbit outside the nucleus. So the description that a proton has a mass of about 1 amu is the correct one. The statements about negative charge, being outside the nucleus, or having a mass around 2 amu do not fit the actual properties of a proton.