Which of the following is the number of protons in a chlorine atom?

• A. 35
• B. 17
• C. 18
• D. 16

Answer: (B)

Verified step by step guidance

1. Recall that the number of protons in an atom is given by its atomic number, which is unique to each element.
2. Identify chlorine on the periodic table; chlorine has the atomic number 17.
3. Understand that the atomic number (number of protons) does not change with isotopes, so regardless of the isotope (like chlorine-35), the number of protons remains 17.
4. Recognize that the number 35 in chlorine-35 refers to the mass number (protons + neutrons), not the number of protons.
5. Therefore, the number of protons in a chlorine atom is equal to its atomic number, which is 17.