Final answer:
CO₂ (carbon dioxide) is the nonpolar molecule among the given options because its linear geometry results in the cancelation of the dipoles from the polar carbon-oxygen bonds.
Step-by-step explanation:
The question is asking which of the following molecules is nonpolar: a) HCl, b) CO₂, c) CH₃Cl, d) HNO₃. To determine polarity, we look at both molecular geometry and difference in electronegativity between atoms. A nonpolar molecule generally has a symmetrical distribution of electrons and the atoms share electrons equally or nearly equally.
b) CO₂ or carbon dioxide is a nonpolar molecule. Despite the fact that the bonds between carbon and oxygen are polar due to differences in electronegativity, the linear geometry of the molecule means that the dipoles cancel each other out, resulting in no overall dipole moment.
Other options: a) HCl has a definite polar covalent bond, c) CH₃Cl contains polar bonds with a tetrahedral geometry, which does not cancel out the dipole moments, and d) HNO₃ is also a polar molecule due to its structure and the differences in electronegativity.