Question

Atoms of different elements possessing the same atomic mass are called:

• A. Isotopes
• B. Isomers
• C. Isobars
• D. Molecules

Hint:

Isomers have the same number and types of atoms but differ in the way the atoms are arranged or bonded.

Answer 1

The Correct Option is C

Step 1: Concept.
Different elements have different atomic numbers, so if two atoms of different elements still end up with the same total mass number, their neutron counts must differ to compensate.

Step 2: Match the term.
Atoms fitting this pattern, different elements, same mass number, are called isobars, unlike isotopes, which need the same element, or isomers and molecules, which describe bonded structures, not single atoms.

Step 3: Final Answer.
Atoms of different elements with the same atomic mass are called Isobars.

Answer 2

Sorting the four options by what kind of thing they compare, atoms versus molecules, and same element versus different element, narrows this down fast.

1. Isomers and Molecules: Both of these terms describe groups of bonded atoms, not single atoms being compared to each other. Since the question is about single atoms of different elements, neither of these terms can be the answer.
2. Isotopes: This term needs the same element, meaning the same atomic number, with the neutron count being the only thing that varies. The question specifically asks about different elements, so isotopes cannot fit.
3. Isobars: This is the only remaining term, and it precisely covers different elements, meaning different atomic numbers, that happen to share the same total mass number.

Once molecules and isomers are set aside for describing bonded structures, and isotopes is set aside for requiring the same element, isobars is the only term left that fits atoms of different elements sharing one atomic mass.

So the correct answer is Isobars.