Chemistry

Question Analysis
This question evaluates the student's ability to determine the name of an isotope given the number of protons and neutrons.

Key Concept Explanation
The name of an isotope is formed by combining the element name with the mass number (A).

Step-by-step Solution
1. Identify the number of protons and neutrons: 19 protons and 21 neutrons.
2. Calculate the mass number: 19 + 21 = 40.
3. Determine the element with 19 protons: potass...