See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

**Step 1: Determine the molecular formula of diethyl ether** Diethyl ether: $C_2H_5-O-C_2H_5$ Molecular formula: $C_4H_{10}O$ **Step 2: Check molecular formulas of each option** - (A) Methyl n-propyl ether: $CH_3-O-C_3H_7$ = $C_4H_{10}O$ ✓ - (B) 1-butanol: $C_4H_9OH$ = $C_4H_{10}O$ ✓ - (C) 2-methyl propan-2-ol: $(CH_3)_3COH$ = $C_4H_{10}O$ ✓ - (D) Butanone: $CH_3-CO-C_2H_5$ = $C_4H_8O$ ✗ **Step 3: Identify the non-isomer** Butanone has the formula $C_4H_8O$, which differs from diethyl ether ($C_4H_{10}O$) by two hydrogen atoms. Since isomers must have the **same molecular formula**, butanone is **not isomeric** with diethyl ether. Options (A), (B), and (C) are all functional group isomers of diethyl ether (all have $C_4H_{10}O$). **Answer: (D) butanone**