Question

The correct order of a dipole moment is :

• A. $C{H}_4<N{F}_3<N{H}_3<H_{2}O$
• B. $NF<C{H}_4<N{H}_3<H_{2}O$
• C. $N{H}_3<N{F}_3<C{H}_4<H_{2}O$
• D. $H_{2}O<N{H}_3<N{F}_3<C{H}_4$

Answer 1

The correct option is A $C{H}_4<N{F}_3<N{H}_3<H_{2}O$

The correct order of dipole moment is $C{H}_4<N{F}_3<N{H}_3<H_{2}O$.
methane is zero dipole moment as it is tetrahedral molecule in which $C-H$ bond dipoles cancel each other.
In $N{F}_3$, the bond dipole of the lone pair and the resultant dipole of three $N-F$ bonds are in opposite direction wheres in ammonia, they are in same direction. Hence, the dipole moment of $N{F}_3$ is smaller than that of methane.
The dipole moment of water is greater than the dipole moment of ammonia as oxygen is more electronegative than nitrogen.