A Level Physics Practice Exam

What do protons and neutrons have in common?

1. Their different charges

2. Their almost equal mass

3. Their ability to bond

4. Their positive charge

The correct answer is: Their almost equal mass

Protons and neutrons share several fundamental characteristics, one of which is their almost equal mass. Both protons and neutrons have masses that are approximately one atomic mass unit (amu). This similarity in mass is significant because it plays a crucial role in the structure of atomic nuclei. Although protons are positively charged and neutrons are neutral, their similar masses allow them to contribute similarly to the atomic structure and stability. Mass is an essential factor in nuclear physics as it influences the binding energy of the nucleus, which determines how stable the nucleus is against decay. This interconnectedness between their masses highlights why protons and neutrons are grouped together as nucleons within the nucleus of an atom, impacting many phenomena in nuclear physics and chemistry.