Let's analyze each statement:

This statement is incorrect. A molecule can have polar bonds but be nonpolar overall if the bond dipoles cancel out due to the molecule's symmetrical geometry. For example, ${\text{CO}}_2$ has two polar C=O bonds, but its linear geometry results in a net dipole moment of zero, making it a nonpolar molecule.

This statement is incorrect. To determine the geometry of ${\text{ClF}}_3$, we use VSEPR theory. The central atom is Cl. Chlorine has 7 valence electrons. Three F atoms form single bonds, and there are two lone pairs on Cl. Thus, the steric number is 3 (bond pairs) + 2 (lone pairs) = 5. This corresponds to a trigonal bipyramidal electron geometry. The lone pairs occupy equatorial positions to minimize repulsion, resulting in a T-shaped molecular geometry. A T-shaped molecule is planar.

This statement is incorrect. The bond angle in Group 15 hydrides decreases down the group. This is because as the size of the central atom increases, its electronegativity decreases, and the bond pair-bond pair repulsion decreases. Also, the bond length increases, and the s-character in the hybrid orbitals forming the bond decreases. The order of bond angles is: ${\text{NH}}_3(107.8^{\circ })>{\text{PH}}_3(93.5^{\circ })>{\text{AsH}}_3(91.8^{\circ })>{\text{SbH}}_3(91.3^{\circ })$. Therefore, the given order is reversed.

This statement is correct. For ${\text{XeF}}_6$, the central atom is Xe. Xenon has 8 valence electrons. Six F atoms form single bonds, and there is one lone pair on Xe. Thus, the steric number is 6 (bond pairs) + 1 (lone pair) = 7. This corresponds to a pentagonal bipyramidal electron geometry. However, due to the presence of one lone pair, the molecular geometry is a distorted octahedral (or capped octahedral) to minimize lone pair-bond pair repulsions. The lone pair occupies a position that distorts the perfect octahedral arrangement.

Correct Answer: (D)