Which of the following is a polar molecule? A CCl₄ B NH₃ C CO₂ D CH₄ - Scottish Highers Chemistry - Question 2 - 2019

To determine which molecule is polar, we need to evaluate the molecular geometry and the electronegativity differences between atoms in each option.

1. CCl₄ (Carbon Tetrachloride): The molecule has a symmetrical tetrahedral shape. Although the C-Cl bonds are polar, the symmetrical geometry results in a nonpolar molecule as the dipoles cancel out.

2. NH₃ (Ammonia): Ammonia has a trigonal pyramidal shape, leading to a net dipole moment due to the lone pair on nitrogen. The nitrogen atom is more electronegative than hydrogen, resulting in a polar molecule.

3. CO₂ (Carbon Dioxide): This molecule has a linear geometry. While the C=O bonds are polar, the symmetrical shape causes the dipoles to cancel each other out, making it nonpolar.

4. CH₄ (Methane): Methane has a tetrahedral shape and is symmetrical. The C-H bonds are not significantly polar, resulting in a nonpolar molecule.

Based on this analysis, the only polar molecule among the options is NH₃ (Ammonia).