A Level Physics Practice Exam

What is the mass of a proton?

1. 1.67 × 10^-23 kg

2. 1.67 × 10^-27 kg

3. 1.67 × 10^-30 kg

4. 1.67 kg

The correct answer is: 1.67 × 10^-27 kg

The mass of a proton is approximately 1.67 × 10^-27 kg. This value is significant in atomic physics as it helps define the scale of subatomic particles. Protons are found in the nucleus of an atom and, along with neutrons, make up most of the atom's mass. The mass of a proton is roughly 1836 times that of an electron, which emphasizes its role in the stability and structure of matter. The incorrect options can be understood in the context of the typical masses of particles. A value of 1.67 × 10^-23 kg would be too large, while 1.67 × 10^-30 kg would be too small, as it falls below the mass scale of even fundamental particles. Similarly, a mass of 1.67 kg is far too large and would not represent the mass of any individual subatomic particle, as it approaches the mass of everyday macroscopic objects. Hence, the choice indicating 1.67 × 10^-27 kg is indeed the accurate representation of the mass of a proton.