Question

How many nonbonding electron pairs does the molecule PCl₃ have?

1) 0
2) 1
3) 2
4) 3

Answer 1

Phosphorus trichloride (PCl3) has one nonbonding electron pair, resulting from the phosphorus atom's trigonal pyramidal molecular geometry.

Step-by-step explanation:

The molecule PCl3 (phosphorus trichloride) contains a phosphorus (P) atom with five valence electrons. These combine with electrons from three chlorine (Cl) atoms to form three P-Cl bonds. In PCl3, there are three electron pairs that participate in bonding, leaving the phosphorus atom with one lone pair of electrons due to its trigonal pyramidal molecular geometry. Therefore, the molecule of phosphorus trichloride (PCl3) has one nonbonding electron pair.