Explain the following:
(i) Boron has high melting and boiling points.

(ii) Aluminium is a good reducing agent. 

Why boron forms electron deficient compounds?

Discuss the characteristics of Group-13 elements in terms of metallic character and their tendency to exhibit inert pair effect. 

Boron chloride exists a monomer while in the same group anhydrous, AlCl₃ exists as a dimer?

White fumes appear around the bottle of anhydrous aluminium chloride.
Or
Why aluminium chloride in air?

Describe the shapes of BF₃ and . Assign the hybridization of boron in these species ?

Suggest a reason why the B - F bond lengths in BF₃ (130 pm) and  (143 pm) differ?
Or
Why B - F bond length in BF₃ is smaller than the expected value?

If B – Cl bond has a dipole moment, why does BCl₃ has zero dipole moment ?

What happens when:
Aluminium is treated with dilute NaOH.

What happens when:
BF₃ is treated with ammonia?