Final answer:
The polar molecule among the given options is HCl because chlorine has a higher electronegativity than hydrogen, creating an uneven pull on the electrons.
Step-by-step explanation:
A polar molecule is one that has a positive and negative charge on opposite ends, which creates a separation of charge. In other words, the molecule has a dipole moment. To determine which of the given molecules is polar, we need to look at the arrangement of the atoms and the electronegativity difference between them.
- O₂: Oxygen is nonpolar because the molecule is symmetric, with the two oxygen atoms pulling on electrons by exactly the same amount.
- HCl: Hydrogen chloride is polar because the chlorine atom has a higher electronegativity than the hydrogen atom, creating an uneven pull on the electrons.
- CH₄: Methane is nonpolar because it is a symmetric molecule, with the four hydrogen atoms bonded to the carbon atom and no unshared pairs of electrons.
- F₂: Fluorine is nonpolar because it is a symmetric molecule, with the two fluorine atoms pulling on electrons by exactly the same amount.