Which property determines the identity of the element mercury?

• A. The number of electrons in the outer shell
• B. The number of neutrons in the nucleus
• C. The number of protons in the nucleus
• D. The atomic mass of the atom

Answer: (C)

Verified step by step guidance

1. Understand that the identity of an element is defined by a fundamental property of its atoms.
2. Recall that atoms consist of protons, neutrons, and electrons, but only one of these determines the element's identity.
3. Recognize that the number of protons in the nucleus, also called the atomic number, uniquely identifies an element.
4. Note that the number of electrons in the outer shell affects chemical behavior but does not change the element itself.
5. Understand that the number of neutrons and the atomic mass can vary within atoms of the same element (isotopes), so they do not determine the element's identity.