How many protons are present in an atom of argon?

• A. 8
• B. 18
• C. 20
• D. 40

Answer: (B)

Verified step by step guidance

1. Identify the element in question, which is argon in this case.
2. Recall that the number of protons in an atom is equal to the atomic number of the element.
3. Look up the atomic number of argon on the periodic table; the atomic number is the number of protons in the nucleus of an atom of that element.
4. Note that argon's atomic number is 18, meaning it has 18 protons.
5. Therefore, the number of protons in an atom of argon is 18.