Chemistry

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

Key Concept Explanation
The number of neutrons in an isotope can be found 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: mass number (A) = 40, atomic number (Z) = 19.
2. Use the formula: Number of neutrons = Mass number - Atomic nu...