Chemistry

Question Analysis
This question tests the student's understanding of the relationship between protons, neutrons, and the mass number of an isotope.

Key Concept Explanation
The mass number of an atom is the sum of the number of protons and neutrons in the nucleus.

Step-by-step Solution
1. Identify the number of protons: 17.
2. Identify the number of neutrons: 20.
3. Calculate the mass number: 17 + 20 = 37.
4. Ther...