What is the mass number of an atom that contains 3 protons, 4 neutrons, and 3 electrons?

• A. 7
• B. 3
• C. 10
• D. 4

Answer: (A)

Verified step by step guidance

1. Identify the number of protons, neutrons, and electrons given in the problem: 3 protons, 4 neutrons, and 3 electrons.
2. Recall that the mass number of an atom is the total number of protons and neutrons in its nucleus. Electrons have negligible mass and do not contribute to the mass number.
3. Write the formula for the mass number: \(\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}\).
4. Substitute the given values into the formula: \(\text{Mass Number} = 3 + 4\).
5. Add the numbers to find the mass number (do not calculate the final sum here, just set up the expression).