Which particles have no charge and weigh 1 amu?

Which particles have no charge and weigh 1 amu?

• A. Protons
• B. Neutrons
• C. Electrons
• D. Quarks

Answer: (B)

The main idea is a neutral particle with a mass close to one atomic mass unit. The neutron fits this: it has no net electric charge and its mass is about 1 amu (roughly 1.0087 amu). Protons have a positive charge, so they don’t meet the charge condition. Electrons are negatively charged and have a tiny mass (about 1/1836 of an amu), so they’re far from 1 amu. Quarks carry fractional charges and have masses much smaller than 1 amu; they’re not observed free and do not independently weigh 1 amu. So the neutron is the particle that is electrically neutral and has a mass of about 1 amu.

The main idea is a neutral particle with a mass close to one atomic mass unit. The neutron fits this: it has no net electric charge and its mass is about 1 amu (roughly 1.0087 amu). Protons have a positive charge, so they don’t meet the charge condition. Electrons are negatively charged and have a tiny mass (about 1/1836 of an amu), so they’re far from 1 amu. Quarks carry fractional charges and have masses much smaller than 1 amu; they’re not observed free and do not independently weigh 1 amu. So the neutron is the particle that is electrically neutral and has a mass of about 1 amu.