An atom has 20 electrons and 20 neutrons. What is the atomic mass of this atom if it also has 20 protons?

• A. 60 amu
• B. 20 amu
• C. 80 amu
• D. 40 amu

Answer: (D)

Verified step by step guidance

1. Understand that the atomic mass of an atom is primarily determined by the sum of the number of protons and neutrons in its nucleus. Electrons have negligible mass and do not significantly contribute to the atomic mass.
2. Identify the number of protons in the atom. According to the problem, the atom has 20 protons.
3. Identify the number of neutrons in the atom. The problem states that the atom has 20 neutrons.
4. Calculate the atomic mass by adding the number of protons and neutrons together. Use the formula: $\mathrm{Atomic}\mathrm{Mass}=\mathrm{Protons}+\mathrm{Neutrons}$
5. Substitute the values into the formula: $20+20$. This will give you the atomic mass of the atom.