See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution To find which is NOT a metameric isomer of $C_4H_{10}O$, I need to check the molecular formula of each compound. **Metamers** are isomers with the same molecular formula but different positions of the functional group (or heteroatom). **Checking each option:** **(1) Diethyl ether:** $C_2H_5-O-C_2H_5$ - Molecular formula: $C_4H_{10}O$ ✓ (Ether) **(2) Methyl n-propyl ether:** $CH_3-O-C_3H_7$ - Molecular formula: $C_4H_{10}O$ ✓ (Ether) **(3) 2-Methoxy propane:** $CH_3-O-CH(CH_3)_2$ - Molecular formula: $C_4H_{10}O$ ✓ (Ether) **(4) Isobutyl alcohol:** $(CH_3)_2CH-CH_2-OH$ - Molecular formula: $C_4H_{10}O$ ✓ (Alcohol) **Key point:** Options (1), (2), and (3) are **ethers** with the same molecular formula—they are functional group isomers (metamers). Option (4) is an **alcohol**, which represents a different functional group class, not just a positional/metameric difference within the same functional group. **Answer: (4) Isobutyl alcohol** is NOT a metameric isomer because it belongs to a different functional group class (alcohol vs. ether). Metamers must have the same functional group but differ in position.