Can the atomic mass of an element vary, and if so, what is the reason for this variation?

• A. Yes, because the number of protons in an element can change.
• B. No, atomic mass only depends on the number of electrons.
• C. Yes, because elements can have different isotopes with varying numbers of neutrons.
• D. No, the atomic mass of an element is always the same for all atoms.

Answer: (C)

Verified step by step guidance

1. Understand that the atomic mass of an element is the weighted average mass of all its naturally occurring isotopes.
2. Recall that isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
3. Recognize that because isotopes differ in neutron number, their masses differ, causing variation in atomic mass.
4. Note that the number of protons defines the element and does not change, so atomic mass variation is not due to proton number changes.
5. Conclude that the atomic mass varies due to the presence of isotopes with different neutron counts, not because of changes in electrons or protons.