Chemistry

Question Analysis
This question tests the student's ability to calculate the number of neutrons in an isotope given its atomic number and mass number.

Key Concept Explanation
The number of neutrons in an isotope is determined by subtracting the atomic number (number of protons) from the mass number (total number of protons and neutrons).

Step-by-step Solution
1. Identify the given values: atomic number (Z) = 15, mass number (A) = 31.
2. Use the formula: Number of neutrons = Mass number - Atomic numbe...