Which of the following best describes the molecular geometry and polarity of carbon tetrabromide (CBr_4)?

• A. Square planar geometry; nonpolar molecule
• B. Tetrahedral geometry; nonpolar molecule
• C. Tetrahedral geometry; polar molecule
• D. Trigonal planar geometry; polar molecule

Answer: (B)

Verified step by step guidance

1. Identify the central atom and the atoms bonded to it in carbon tetrabromide (CBr_4). Here, carbon (C) is the central atom bonded to four bromine (Br) atoms.
2. Determine the number of electron groups around the central atom. Carbon has four single bonds to bromine atoms, so there are four bonding pairs and no lone pairs on carbon.
3. Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the molecular geometry. Four bonding pairs with no lone pairs around the central atom arrange themselves to minimize repulsion, resulting in a tetrahedral geometry.
4. Assess the polarity of the molecule by considering the symmetry and the electronegativity difference between carbon and bromine. Since the molecule is symmetrical with identical bonds arranged tetrahedrally, the dipole moments cancel out, making the molecule nonpolar.
5. Conclude that carbon tetrabromide (CBr_4) has a tetrahedral molecular geometry and is a nonpolar molecule.