StudyStore

Free MCAT-style practice, 5B

MCAT VSEPR, Hybridization and Molecular Geometry Practice Questions

By StudyStore · Published 2026-11-04 · 8 original questions · about 12 min

Eight free MCAT-style chemistry practice questions on VSEPR geometry, sp, sp2 and sp3 hybridization, bond angles, sigma and pi bonds and molecular polarity, with explanations.

Email me free MCAT notes, practice sets and new packs from StudyStore. Double opt-in, unsubscribe in one click. Privacy

Quick concept primer

VSEPR theory predicts shape by counting electron groups around the central atom (bonds and lone pairs); groups repel and spread out. Two groups give linear (180 degrees, sp), three give trigonal planar (120 degrees, sp2), and four give tetrahedral (109.5 degrees, sp3). Lone pairs occupy space but are not counted in the molecular shape name: ammonia (3 bonds, 1 lone pair) is trigonal pyramidal, and water (2 bonds, 2 lone pairs) is bent. Lone pairs compress bond angles slightly.

A single bond is one sigma bond; a double bond is one sigma plus one pi bond; a triple bond is one sigma plus two pi bonds. Pi bonds come from unhybridized p orbitals and prevent rotation. A molecule is polar only if it has polar bonds whose dipoles do not cancel, so symmetry matters: CO2 and CCl4 are nonpolar despite polar bonds.

8 practice questions

Try each question before opening the explanation. Click "Show answer and explanation" to check yourself. All questions are original and written for study practice.

Question 1

What is the molecular geometry and hybridization of the carbon atom in methane, CH4?

  1. Trigonal planar, sp2
  2. Linear, sp
  3. Tetrahedral, sp3
  4. Bent, sp3
Show answer and explanation

Answer: C. Tetrahedral, sp3

Carbon in methane has four bonding groups and no lone pairs, so the geometry is tetrahedral with bond angles of 109.5 degrees. Four groups require four hybrid orbitals, an sp3 set.

Question 2

What is the molecular geometry of ammonia, NH3?

  1. Trigonal planar
  2. Trigonal pyramidal
  3. Tetrahedral
  4. Bent
Show answer and explanation

Answer: B. Trigonal pyramidal

Nitrogen has four electron groups: three bonds and one lone pair. The electron geometry is tetrahedral, but the molecular shape, which describes only the atoms, is trigonal pyramidal. The lone pair pushes the bond angle to about 107 degrees.

Question 3

What is the hybridization of the carbon atom in carbon dioxide, CO2, and what is the O-C-O bond angle?

  1. sp2, 120 degrees
  2. sp3, 109.5 degrees
  3. sp, 180 degrees
  4. sp, 90 degrees
Show answer and explanation

Answer: C. sp, 180 degrees

Carbon forms two double bonds, which means two electron groups, so it is sp hybridized and the molecule is linear with a 180 degree angle. The two unhybridized p orbitals make the pi bonds.

Question 4

Water is bent with a bond angle near 104.5 degrees instead of 109.5 degrees. What best explains the smaller angle?

  1. Oxygen is sp hybridized
  2. Water has only one lone pair on oxygen
  3. The O-H bonds are nonpolar
  4. Lone pairs repel bonding pairs more strongly than bonding pairs repel each other
Show answer and explanation

Answer: D. Lone pairs repel bonding pairs more strongly than bonding pairs repel each other

Oxygen has four electron groups, two bonds and two lone pairs, so it is roughly tetrahedral. Lone pairs take more space than bonding pairs and squeeze the bond angle. This is also why ammonia (107 degrees) is smaller than methane's 109.5 degrees.

Question 5

Which molecule is trigonal planar and nonpolar?

  1. BF3
  2. NH3
  3. H2O
  4. CHCl3
Show answer and explanation

Answer: A. BF3

Boron trifluoride has three bonding groups and no lone pairs, so it is trigonal planar with sp2 boron. The three polar B-F dipoles cancel by symmetry. Ammonia and water are polar because their lone pairs make the shape asymmetric.

Question 6

Which description of ethene, H2C=CH2, is correct?

  1. Each carbon is sp3 and the molecule is tetrahedral
  2. Each carbon is sp and the molecule is linear
  3. The C=C bond has two sigma bonds
  4. Each carbon is sp2, the C=C bond is one sigma and one pi bond, and the molecule is planar
Show answer and explanation

Answer: D. Each carbon is sp2, the C=C bond is one sigma and one pi bond, and the molecule is planar

Each carbon has three sigma bonds (two C-H and one C-C) and an unhybridized p orbital that makes the pi bond. Three groups give sp2 and a planar structure with bond angles near 120 degrees. The pi bond restricts rotation about the double bond.

Question 7

How many sigma bonds and how many pi bonds are in ethyne (acetylene), HC triple-bond CH?

  1. 3 sigma and 2 pi
  2. 2 sigma and 3 pi
  3. 1 sigma and 2 pi
  4. 5 sigma and 0 pi
Show answer and explanation

Answer: A. 3 sigma and 2 pi

Two C-H bonds are sigma and the triple bond contributes one sigma and two pi bonds, for 3 sigma and 2 pi in total. Each carbon is sp hybridized and the molecule is linear.

Question 8

Carbon tetrachloride, CCl4, has polar C-Cl bonds. Why is the molecule nonpolar?

  1. The C-Cl bonds are nonpolar covalent
  2. The tetrahedral geometry makes the bond dipoles cancel
  3. Chlorine has the same electronegativity as carbon
  4. It has lone pairs on carbon
Show answer and explanation

Answer: B. The tetrahedral geometry makes the bond dipoles cancel

Chlorine is more electronegative than carbon, so each C-Cl bond is polar, but the four dipoles point to the corners of a tetrahedron and sum to zero. Molecular polarity depends on both bond polarity and geometry.

Free MCAT sampler

Free sample: MCAT cheat sheet (PDF)

Join the list and download a free sample from a paid pack: the 3-page Amino Acids, Proteins and Enzymes cheat sheet (PDF). We also email free MCAT notes and practice sets.

Free sampler, no signup needed: 51 study notes with original diagrams and 5-question quizzes, 80 practice sets (706 questions with full explanations) and the 2027 study schedule generator.

Email me free MCAT notes, practice sets and new packs from StudyStore. Double opt-in, unsubscribe in one click. Privacy

Keep practicing

Written by StudyStore from standard scientific facts as a study aid. These are not official exam questions and are not affiliated with or endorsed by any testing organization. Always check values against the reference provided with your exam or course.

Spotted a mistake in a question? Report a problem or suggest something