Molecular & Ionic Compound Structure/Properties

The BF₃ molecule is nonpolar, whereas the NF₃ molecule is polar. Which of the following statements accounts for the difference in polarity of the two molecules?

• In NF₃, each F is joined to N with multiple bonds, whereas in BF₃ , each F is joined to B with single bonds.

• N — F bonds are polar, whereas B — F bonds are nonpolar.

• NF₃ is an ionic compound, whereas BF₃ is a molecular compound.

• Unlike BF₃, NF₃ has a nonplanar geometry due to an unshared pair of electrons on the N atom.

Which of the following is a nonpolar molecule that contains polar bonds?

• F₂

• CHF₃

• CO₂

• HCl (hydrogen chloride)

• NH₃

The electron-dot structure (Lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom?

• H₂S

• NH₃

• CH₄

• HCN

• CO₂

According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH₄, NH₃, and H₂O is best accounted for by the:

• increasing strength of the bonds.

• decreasing size of the central atom.

• increasing electronegativity of the central atom.

• increasing number of unshared pairs of electrons.

Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams best represents the particle-level structure of steel?

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Which of the following molecules has the shortest bond length?

• N₂

• O₂

• Cl₂

• Br₂

• I₂

Which of the following diagrams best depicts an alloy of Ni and B?

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Of the following diagrams, which best represents the structure of solid KF?

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Which of the following arranges the molecules N₂, O₂, and F₂ in order of their bond enthalpies, from least to greatest?

• F₂ < O₂ < N₂

• O₂ < N₂ < F₂

• N₂ < O₂ < F₂

• N₂ < F₂ < O₂

Which of the following molecules contains polar covalent bonds but is a nonpolar molecule?

• CH₃Cl

• CH₂Cl₂

• NH₃

• CCl₄

• N₂