An example of a polar covalent compound is : A. KCl B. NaCl C. CCl4 D. HCl
The correct answer and explanation is:
Correct Answer: D. HCl
A polar covalent compound is one in which atoms share electrons unequally due to a difference in their electronegativities. This unequal sharing results in a molecule that has a partial positive charge on one end and a partial negative charge on the other, creating a dipole.
Hydrogen chloride (HCl) is a classic example of a polar covalent compound. It consists of a hydrogen atom bonded to a chlorine atom. Chlorine is significantly more electronegative than hydrogen. This difference causes chlorine to attract the shared electrons more strongly, resulting in a partial negative charge (δ–) on the chlorine atom and a partial positive charge (δ+) on the hydrogen atom. This uneven distribution of charge gives HCl its polar nature.
In contrast, the other answer choices are not examples of polar covalent compounds:
- A. KCl (potassium chloride) and B. NaCl (sodium chloride) are ionic compounds. These compounds consist of metals (potassium or sodium) and nonmetals (chlorine), where electrons are transferred from the metal to the nonmetal, forming ions. There is no sharing of electrons, so these are not covalent at all.
- C. CCl₄ (carbon tetrachloride) is a nonpolar covalent compound. Although each individual C–Cl bond is polar due to the difference in electronegativity, the molecule has a symmetrical tetrahedral shape. This symmetry causes the individual dipoles to cancel out, resulting in a nonpolar molecule overall.
HCl, with its single polar bond and no symmetry to cancel the dipole, clearly fits the definition of a polar covalent compound. It is widely used in chemistry as an example of this type of bond and helps illustrate the importance of electronegativity and molecular shape in determining polarity.