Question

The number of planes of symmetry in this compound is :

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (C)

3

Answer 2

The given compound is naphthalene, which has a D₂h symmetry. In this point group, there are three mutually perpendicular planes of symmetry:

• One horizontal plane (the molecular plane)

• Two vertical planes (one along the long axis and one perpendicular to it)

Thus, there are 3 planes of symmetry.

Naphthalene belongs to the D₂h group which has three mirror planes (one in the molecular plane and two vertical).