Chemistry

Question Analysis
This question tests the student's understanding of the concept of mass number, which is the sum of the number of protons and neutrons in an atom.

Key Concept Explanation
The mass number of an isotope is determined by adding the number of protons and neutrons in the nucleus. Protons and neutrons are collectively known as nucleons.

Step-by-step Solution
1. Identify the number of protons: 7
2. Identify the number of neutrons: 8
3. Calculate the mass number: 7 (p...