Which of the following pairs of compounds are isomers?

• A. C2H6O (ethanol) and C2H6O (dimethyl ether)
• B. H2O and H2O2
• C. C3H8 and C3H6
• D. CH4 and C2H6

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the definition of isomers. Isomers are compounds that have the same molecular formula but different structural arrangements of atoms.
2. Step 2: Examine each pair of compounds to see if they share the same molecular formula. For example, check if both compounds in a pair have the same number and type of atoms.
3. Step 3: For the pair C2H6O (ethanol) and C2H6O (dimethyl ether), confirm that both have the molecular formula C2H6O but differ in structure: ethanol has an -OH group attached to an ethyl group, while dimethyl ether has an oxygen atom connecting two methyl groups.
4. Step 4: For other pairs, compare their molecular formulas: H2O vs H2O2, C3H8 vs C3H6, and CH4 vs C2H6. Since their formulas differ, they cannot be isomers.
5. Step 5: Conclude that only the pair with the same molecular formula but different structures (C2H6O compounds) are isomers.