Question

In PCl\(_5\) molecule, the angle Cl-P-Cl present in a plane is equal to

• A. 180°
• B. 120°
• C. 90°
• D. 104°

Hint:

In a trigonal bipyramidal geometry, the equatorial positions have 120° angles between them.

Answer 1

The Correct Option is B

Step 1: Understanding the molecular geometry of PCl\(_5\).
PCl\(_5\) has a trigonal bipyramidal structure. In this geometry, the three chlorine atoms in the equatorial plane form 120° angles with each other. The axial chlorine atoms are positioned at 90° angles with the equatorial plane.

Step 2: Analyzing the options.
(A) 180°: This is incorrect. The angle between two chlorines in the same plane is 120°.
(B) 120°: Correct — In the equatorial plane of a trigonal bipyramidal molecule, the chlorine atoms are at 120° from each other.
(C) 90°: This is incorrect. The 90° angle is between the axial and equatorial chlorine atoms.
(D) 104°: This is incorrect. The 104° angle is characteristic of a bent geometry, like in H\(_2\)O, not PCl\(_5\).

Step 3: Conclusion.
The correct angle is (B) 120°.