(1)

${\mathrm{NH}}_3$ : Trigonal pyramidal (A–I)
${\mathrm{BrF}}_5$ : Square pyramidal (B–IV)
${\mathrm{XeF}}_4$ : Square planar (C–II)
${\mathrm{SF}}_6$ : Octahedral (D–III)
 

(4)

${\mathrm{ClF}}_3,{\mathrm{IF}}_5,{\mathrm{SF}}_4$ and ${\mathrm{XeF}}_2$ contain 2, 1, 1 and 3 lone pairs of electrons on the central atom respectively. Hence, ${\mathrm{XeF}}_2$ has maximum lone pair - lone pair repulsions.
 

(2)

$PC{l}_5$   :  Trigonal bipyramidal
$S{F}_6$     :  Octahedral
$Br{F}_5$    :  Square pyramidal
$B{F}_3$     :  Trigonal planar

(2)

The structure of ${\mathrm{ClF}}_3$ is

[IMAGE 18]--------------------------

Hence, Cl has 2 lone pairs of electrons.

(3)

According to VSEPR theory, the repulsive forces between lone pair and lone pair are greater than between lone pair and bond pair which are further greater than bond pair and bond pair.