Questions: Which of the following has the least ring strain? I II III IV V

Solution Steps

• The shapes given are polygons with different numbers of sides:
  • I: Octagon (8 sides)
  • II: Pentagon (5 sides)
  • III: Hexagon (6 sides)
  • IV: Square (4 sides)
  • V: Triangle (3 sides)

• Ring strain in cyclic compounds arises from angle strain, torsional strain, and steric strain.
• Angle strain occurs when bond angles deviate from their ideal values (109.5° for sp3 hybridized carbons).

• Hexagon (III) has bond angles of 120°, which is close to the ideal tetrahedral angle, minimizing angle strain.
• Octagon (I) and Pentagon (II) have more angle strain due to deviation from ideal angles.
• Square (IV) and Triangle (V) have significant angle strain due to their small bond angles (90° and 60° respectively).

Final Answer