Match the CH_3-C2-C3-CH_3 dihedral angles of butane in Column I with the conformation type in Column II. Column I: (P) 0 deg; (Q) 60 deg; (R) 120 deg; (S) 180 deg. Column II: (1) anti (staggered); (2) gauche (staggered); (3) fully eclipsed (syn-periplanar); (4) partially eclipsed (anticlinal).

JEE Main levelSingle correct optionDifficulty 2 of 3st208

Match the CH $_{3}$ -C2-C3-CH $_{3}$ dihedral angles of butane in Column I with the conformation type in Column II. Column I: (P) $0^{\circ}$ ; (Q) $6 0^{\circ}$ ; (R) $12 0^{\circ}$ ; (S) $18 0^{\circ}$ . Column II: (1) anti (staggered); (2) gauche (staggered); (3) fully eclipsed (syn-periplanar); (4) partially eclipsed (anticlinal).

A 0

^{\circ}

dihedral puts the two methyls on top of each other (fully eclipsed, highest energy). At 60

^{\circ}

the groups are staggered and close (gauche). At 120

^{\circ}

the CH

_{3}

groups are eclipsed with H atoms (partially eclipsed, anticlinal). At 180

^{\circ}

they are staggered and opposite (anti, lowest energy). So P-3, Q-2, R-4, S-1.