AP Chemistry: 2.7 VSEPR and Bond Hybridization – Exam Style questions with Answer- MCQ

Question

Which of the following Lewis diagrams represents a molecule that is polar?

▶️Answer/Explanation

Ans:C

In the \(CH_2Cl_2\) molecule, the H and Cl atoms are in a tetrahedral arrangement around the central C atom. The two electronegative chlorine atoms create a partial negative charge on their side of the carbon atom, leaving a partial positive charge on the opposite (hydrogen) side of the carbon atom. This separation of charge constitutes a dipole, and the molecule is polar.

Question

Which of the following correctly compares the strength of the two carbon-to-carbon bonds in the molecule represented in the Lewis diagram shown above?

A The carbon-to-carbon bond on the left is stronger because it is a double bond.
B The carbon-to-carbon bonds are the same strength because the C-C-C bond angle is 180°.
C The carbon-to-carbon bonds are the same strength because they are both bonds between carbon atoms.
D The carbon-to-carbon bond on the right is stronger because there are more hydrogen atoms attached to the rightmost carbon atom than to the leftmost carbon atom.
▶️Answer/Explanation

Ans:A

Double bonds between two atoms are always stronger than single bonds between those same two atoms because in a double bond there are more electrons between the two positive nuclei of the atoms, which results in a stronger bond.

 

Based on the Lewis diagram for \(NH_3\) , shown above, the H-N-H bond angle is closest to which of the following?

A 60°

B 90°

C 109.5°

D 120°

▶️Answer/Explanation

Ans:C

With four electron domains around the central N atom, their geometry is tetrahedral (which minimizes repulsion among the four electron pairs). The tetrahedral angle is 109.5°; therefore, the H-N-H bond angle is approximately 109.5°.

Question

The structural formula of the glycinium cation is shown above. Arrows indicate the \( pK_{ a}\) values for the labile protons in the molecule.

What is the approximate H-O-C bond angle in the  glycinium  cation?
(A) 180°
(B) 120°
(C) 105°
(D) 90°

▶️Answer/Explanation

Ans:A

The structural formula of the glycinium cation is shown above. Arrows indicate the \( pK_{ a}\) values for the labile protons in the molecule.

Question

Which of the following is true about the geometry of the glycinium cation?

(A) The leftmost C atom and all the atoms directly bonded to it lie in the same plane.

(B) Both C atoms and both O atoms lie in the same plane.

(C) The N-C-C bond angle is 180°.

(D) The geometry around the N atom is planar.

▶️Answer/Explanation

Ans:C

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