Isomers are compounds with the same atoms but arranged differently.

• A. Compound with same atoms, arranged differently
• B. Compound with different atoms arranged the same
• C. Compound with identical arrangement
• D. A polymer

Answer: (A)

Isomers share the same atoms but are arranged differently, so they have the same molecular formula yet different connectivity or spatial arrangement. This difference changes properties even though the ingredient set is the same.

For example, butane and isobutane both are C4H10, but their carbon skeletons are arranged differently, so they’re isomers. Similarly, ethanol and dimethyl ether both have the formula C2H6O, but one is an alcohol and the other an ether because the atoms connect in different ways.

The idea described as having different atoms arranged the same would alter the formula, so that isn’t isomerism. Describing identical arrangement would mean the same compound, not an isomer. A polymer is a large repeating structure and isn’t the definition of isomers.