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QuestionChemistry

Potassium’s atomic number is 19, and its atomic mass is approximately 39. How many neutrons does potassium have? A. 19 B. 58 C. 20 D. 39
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Answer

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Step 1:
Let's solve this step by step:

Step 2:
: Understand the given information

- Atomic number of potassium = 19 - Atomic mass of potassium ≈ 39

Step 3:
: Recall the relationship between atomic number, atomic mass, and neutrons

- Atomic number = number of protons - Number of neutrons = Atomic mass - Atomic number

Step 4:
: Calculate the number of neutrons

\text{Number of neutrons} = 39 - 19 = 20

Step 5:
: Verify the calculation

- Protons = 19 - Neutrons = 20 - Total = 39 ✓

Final Answer

Explanation: - The atomic number (19) tells us the number of protons - The atomic mass (39) represents the total number of protons and neutrons - Subtracting the number of protons from the atomic mass gives the number of neutrons - 39 - 19 = 20 neutrons