In the simplified atomic model, what is the approximate mass of one neutron?

• A. About $9.11\times {10}^{\mathrm{-28}}g$ (the mass of an electron)
• B. About $1\times {10}^{\mathrm{-24}}g$ (approximately $1$ amu)
• C. About $1\times {10}^{\mathrm{-20}}g$ (approximately $10000$ amu)
• D. About $1\times {10}^{\mathrm{-28}}g$ (approximately $0.0005$ amu)

Answer: (B)