See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

**Step 1: Determine the molecular formula of both compounds** - $CH_3-NH-C_2H_5$: Contains C (1+2=3), H (3+1+5=9), N (1) → **$C_3H_9N$** - $(CH_3)_3N$: Contains C (3), H (9), N (1) → **$C_3H_9N$** Both have the same molecular formula, confirming they are isomers. **Step 2: Identify the structural difference** - $CH_3-NH-C_2H_5$: Secondary amine with a **branched carbon chain** (methyl + ethyl groups attached to N) - $(CH_3)_3N$: Tertiary amine with a **different carbon arrangement** (three methyl groups attached to N) **Step 3: Classify the type of isomerism** - **Chain isomerism** occurs when the carbon skeleton differs while the functional group remains the same - Both compounds have the amine ($-NH$) functional group intact - The difference lies in how the carbon atoms are arranged/connected around the nitrogen **Answer: (3) Chain isomerism** The two compounds differ in their carbon chain arrangement while maintaining the same amine functional group, making them chain isomers.