How many protons are present in a single atom of sodium (Na)?

• A. 11
• B. 12
• C. 10
• D. 23

Answer: (A)

Verified step by step guidance

1. Identify the element in question, which is sodium (Na). Each element is defined by its atomic number, which represents the number of protons in its nucleus.
2. Recall that the atomic number of sodium (Na) is 11. This number is unique to sodium and can be found on the periodic table.
3. Understand that the number of protons in an atom is equal to its atomic number, so the number of protons in a sodium atom is the same as its atomic number.
4. Therefore, the number of protons in a single sodium atom is 11.
5. Note that the other numbers given (12, 10, 23) correspond to different quantities: 12 could be the number of neutrons in a common isotope, 10 is incorrect for protons, and 23 is the atomic mass number (protons + neutrons) for the most common isotope of sodium.