Neco 2021 Chemistry Question 27

Practice objective / multiple choice question 27 from the 2021 Neco Chemistry examination.

Neco 2021 Chemistry Objective / Multiple Choice Medium Difficulty
Question 27 NECO • 2021 • CHEMISTRY • objective

A molecule AB₂ is planar with a bond angle of 120° and has a measured dipole moment of zero. The central atom A uses sp² hybrid orbitals to form σ‑bonds with two identical atoms B. The electronegativities are χ_A=2.5 and χ_B=3.0. (a) Determine whether each A-B bond is polar or non‑polar. (b) Calculate the percent ionic character of an A-B bond using the formula \\% ionic = (1- e^{-0.25(Δχ)²})\times100, where Δχ is the electronegativity difference. (c) Explain why the molecule is overall non‑polar despite having polar bonds.

Answer Options

Correct Answer A. Each A-B bond is polar; % ionic ≈ 6.06 %; the molecule is non‑polar because the equal bond dipoles cancel by symmetry.
B. Each A-B bond is non‑polar; % ionic ≈ 0 %; the molecule is non‑polar because there are no bond dipoles.
C. Each A-B bond is polar; % ionic ≈ 12.5 %; the molecule is polar because the bond dipoles add vectorially.
D. Each A-B bond is polar; % ionic ≈ 6.06 %; the molecule is polar because the central atom is more electronegative.
Correct Answer
A
Correct Option:
Each A-B bond is polar; % ionic ≈ 6.06 %; the molecule is non‑polar because the equal bond dipoles cancel by symmetry.

About This Question

This is Neco 2021 Chemistry Question 27. It is one of the objective questions from the 2021 Neco Chemistry examination.

Difficulty level: Medium .

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