Question

Select the correct statements.

• A. $N{H}_3$ has higher bond dipole than $N{F}_3$
• B. $CC{l}_4$ is polar molecule
• C. $S{F}_4$ is polar molecule
• D. $I{F}_7$ is polar molecule

Answer 1

The correct option is C $S{F}_4$ is polar molecule

In $N{H}_3$, N is more electronegative than H. So, N pulls the electrons from H towards itself and so, the direction of the moment due to the N-H bonds is in the same direction as that of the lone pair of electrons on Nitrogen. In $N{F}_3$, F is more electronegative than N. But, $N{H}_3$ has more dipole moment than $N{H}_3$.

$CC{l}_4$ is an example of a nonpolar molecule. ... The four bonds of carbon tetrachloride are polar, but the molecule is nonpolar because the bond polarity is canceled by the symmetric tetrahedral shape. When other atoms substitute for some of the Cl atoms, the symmetry is broken and the molecule becomes polar.

If there are some lone pairs of electrons around the central atom, and if there is an odd number, the molecule is polar. Just like this molecule $S{F}_4$. Here, there is only one lone pair around the central atom (Sulfur) which is an odd number. So, $S{F}_4$ is polar.

$I{F}_7$ are nonpolar due to their shape is complex, and the dipole moment is zero or close to it.