Which of the following is the atomic number of sodium?

• A. 12
• B. 23
• C. 22
• D. 11

Answer: (D)

Verified step by step guidance

1. Understand that the atomic number of an element is the number of protons in the nucleus of an atom of that element.
2. Recall that sodium is represented by the chemical symbol Na on the periodic table.
3. Look up sodium (Na) on the periodic table to find its atomic number, which is the number usually located above the element symbol.
4. Note that the atomic number of sodium is 11, meaning it has 11 protons in its nucleus.
5. Recognize that the other numbers given (12, 23, 22) correspond to either the mass number or other unrelated values, not the atomic number.