Which of the following is the atomic number of cobalt?

• A. 27
• B. 59
• C. 29
• D. 24

Answer: (A)

Verified step by step guidance

1. Recall that the atomic number of an element is the number of protons in the nucleus of an atom of that element.
2. Identify the element cobalt (Co) on the periodic table to find its atomic number.
3. Look for the number usually located above the element symbol (Co) on the periodic table, which represents the atomic number.
4. Verify that the atomic number corresponds to the number of protons and defines the element uniquely.
5. Confirm that the atomic number of cobalt is 27, distinguishing it from the other numbers given (59, 29, 24).