Question

which of the following molecules is polar? 1. bh₃ 2. cf₄ 3. nh₃ 4. h₂ 5. ch₄

Explanation:

A polar molecule has a net dipole moment due to an uneven distribution of electron - density. In $BH_3$, it has a trigonal planar geometry and the bond dipoles cancel out, making it non - polar. $CF_4$ has a tetrahedral geometry and the symmetric arrangement of C - F bonds results in a non - polar molecule. $NH_3$ has a trigonal pyramidal geometry with a lone pair on the nitrogen atom. The lone pair - bond pair repulsions cause an uneven electron - density distribution, making it polar. $H_2$ is a homonuclear diatomic molecule with an equal sharing of electrons, so it is non - polar. $CH_4$ has a tetrahedral geometry and the symmetric C - H bonds lead to a non - polar molecule.

Answer:

1. $NH_3$