See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Step 1 — Read the Newman projection. The front carbon bears: Cl (top), H (upper-left), Cl (upper-right). The back carbon bears: H (lower-left), H (bottom), H (lower-right). This represents 1,1-dichloroethane (CHCl2–CH3). The front carbon is CHCl2; the back carbon is CH3. Step 2 — Determine the dihedral angles (conformation). Using the Newman convention, the three substituents on the front carbon are at approximately 12 o'clock (Cl), 10 o'clock (H), and 2 o'clock (Cl). The three substituents on the back carbon are at approximately 8 o'clock (H), 6 o'clock (H), and 4 o'clock (H). This is a gauche/staggered conformation where the two Cl groups are gauche to the back H atoms. Step 3 — Convert to a sawhorse (zigzag) representation. In a sawhorse drawing, the bond between the two carbons is drawn as a diagonal line going from lower-left (back carbon) to upper-right (front carbon). The front carbon is at upper-right and the back carbon is at lower-left. - Front carbon (upper-right) has: H going upper-left, Cl going upper-right (and the C–C bond accounting for the third bond). - Back carbon (lower-left) has: Cl going left, H going lower-left, H going lower-right, H going right. This matches option (b), which shows the front carbon with H (upper-left) and Cl (upper-right), and the back carbon with Cl (left), H, H, H — consistent with CHCl2 on the front carbon and CH3 on the back carbon in the correct staggered conformation. Step 4 — Eliminate other options. (a) Places both Cl atoms on what appears to be the back carbon or in an eclipsed arrangement inconsistent with the Newman projection shown. (c) Distributes one Cl on the front and one Cl on the back carbon, changing the connectivity (this would be 1,2-dichloroethane, not 1,1-dichloroethane). (d) Similarly misassigns the chlorines or uses the wrong dihedral angle. Therefore, the correct answer is B.