Question

Assertion: The order of bond angle of halides of boron is ${\mathrm{BI}}_3>{\mathrm{BBr}}_3>{\mathrm{BCl}}_3>{\mathrm{BF}}_3$.

Reason: Greater is the size of surrounding atom, larger will be the bond angle.

• A. Both assertion and reason are false.
• B. Assertion is true, but the reason is false.
• C. Both assertion and reason are true. The reason is the correct explanation of assertion.
• D. Both assertion and reason are true. The reason is not the correct explanation of assertion.

Answer 1

The correct option is B

Assertion is true, but the reason is false.

The explanation for Assertion statement

• The bond angle is the angle between one bond from the central atom to one surrounding atom and the other bond from the central atom to the second surrounding atom.
• The order of the bond angle of boron trihalide is as follows:

${\mathrm{BI}}_3>{\mathrm{BBr}}_3>{\mathrm{BCl}}_3>{\mathrm{BF}}_3$

The explanation for Reason statement

• Boron is found in the periodic table's second period and ${13}^{\mathrm{th}}$ group.
• Boron has an atomic number of $5$.
• The order of the atomic size of the halogen is as follows:

$\mathrm{F}<\mathrm{Cl}<\mathrm{Br}<\mathrm{I}$

• The large size of the $p$ orbital of halides reduces the effective overlap between orbitals.

Therefore, the correct option is (B) Assertion is true, but the reason is false.