Chemistry

Question Analysis
This question evaluates the student's ability to calculate the atomic mass of an isotope given the number of protons, neutrons, and their respective masses.

Key Concept Explanation
The atomic mass of an isotope is the sum of the masses of its protons and neutrons. The mass of a proton is approximately 1.0073 amu, and the mass of a neutron is approximately 1.0087 amu.

Step-by-step Solution
1. Identify the number of protons and neutrons in the isotope.
2. Number of protons = 20
3. Mass number = 42 → Number of neutrons = 42 - 20 = 22
4. Calculate the total mass of protons:
5. Calculate the total mass of neutrons:

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