Chemistry · Covalent Bonding: Concept of electronegativity, Fajan's rule, dipole moment, Valence Shell Electron Pair Repulsion (VSEPR) theory and shapes of simple molecules
Assertion The bond angle of is greater than but the bond angle of is lesser than
Assertion The bond angle of \( P B r_{3} \) is greater than \( P H_{3} \) but the bond angle of \( N B r_{3} \) is lesser than \( \boldsymbol{N} \boldsymbol{H}_{3} \) Reason Electronegativity of \( P \) -atom is less than that of \( N \) -atom.
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Assertion is incorrect but Reason is correct
Step-by-step solution
The assertion is correct: bond angle of PBr3 (~101°) is greater than PH3 (~93.5°) due to steric repulsion from larger Br atoms, while bond angle of NBr3 (~101°) is less than NH3 (107.8°) due to longer N-Br bonds and higher Br electronegativity reducing lone pair-bond pair repulsion. The reason that P is less electronegative than N is true, but it does not directly explain the contrasting bond angle trends, which involve both steric and electronic effects. Hence, reason is not the correct explanation.