See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Newman Projection Analysis for 2,2-Dimethylbutane **Structure of 2,2-dimethylbutane:** $$CH_3-C(CH_3)_2-CH_2-CH_3$$ The Newman projection shows the view looking down the C2-C3 bond (the central carbon with two methyls attached). **Identifying the groups on C2 (front carbon):** - Two $CH_3$ groups (the two methyls at position 2) - One $H$ atom - The bond extending along the axis (toward C3) **Identifying the groups on C3 (back carbon):** - One $CH_3$ group (the methyl of the ethyl chain) - One $CH_2CH_3$ group (the ethyl chain, represented as $C_2H_5$) - Two $H$ atoms **Determining X and Y:** - **X (top position):** Points upward from C2. This is one of the three substituents on C2. Since two are methyls and one is H, X can be either $H$ or $CH_3$. - **Y (bottom position):** Points downward from C3. The substituents on C3 are: one $CH_3$, one $C_2H_5$, and two $H$ atoms. Y can be $H$, $CH_3$, or $C_2H_5$. **Valid combinations:** - **(B)** $H$ and $C_2H_5$ ✓ - **(D)** $CH_3$ and $CH_3$ ✓ Both are possible depending on the rotational orientation of the bonds in the Newman projection.