Question

Maximum bond angle is present in:
A.$B{F_3}$
B.$BC{l_3}$
C.$BB{r_3}$
D.Same for all

Answer 1

Bond angle is the average angle between the two or more atoms across two bonds. It depends upon the lone pairs; the size of the central atom and the electronegativity of atoms present in the molecule. The presence of more electronegative atoms in the molecule leads to a decrease in the bond angle.

Complete answer:
Given are the three molecules in which the boron is the central atom. These three molecules or compounds are known as boron halides. As boron is attached with the halogens. The central metal atom is the same and the other atoms are belonging to the same group which means having the same valence electrons. Thus, there is no difference in hybridization.
All the three boron halides have $s{p^2}$ hybridization. Thus, the bond angle will be ${120^0}$ with trigonal planar geometry. The three valence electrons on the boron atom were shared by three halide atoms leads to the formation of three covalent bonds. Thus, the hybridization is $s{p^2}$.
But, the presence of an electronegative atom makes the bond angle lower. As the electronegativity of surrounding atoms is high then lower is the bond angle of the compound.
Thus, boron bromide $\left( {BB{r_3}} \right)$ has high bond angle as bromine is less electronegative then the remaining two.

Option C is the correct one.

Note:
Electronegativity is the tendency to attract a shared pair of electrons towards itself. Fluorine is the most electronegative element in the periodic table. The electronegativity decreases along with the group. Thus, bromine is less electronegative than chlorine, chlorine is less electronegative than fluorine.