Question

Which of the following does not show similarity between boron and aluminium?

• A. Both form oxides of type $M_2{O}_3$ when heated with oxygen at high temperature.
• B. Both dissolve in alkalies and evolve hydrogen.
• C. Hydroxides of both the elements are basic in nature.
• D. Both form nitrides of MN type when heated with $N_2$.

Answer 1

Answer: (C)

Hydroxides of both the elements are basic in nature.

Answer:- (C) Hydroxide of both elements are basic in nature

Reason:-

Boron and aluminium both are electrophilic in nature due to the presence of an empty p-orbital. In case of boron, it is 2p orbital, which is small in size and less diffuse, which make its overlap with oxygen's lone pair more effective which increases the acidity of boron hydroxide while In case of aluminium, the 3p orbital is involved and is larger and more diffuse and even the $Al-O$ bond is longer. These properties additively make oxygen's lone pair interaction less effective which results in aluminium hydroxides less acidity.

Thus, the hydroxides of boron and aluminium show different nature and cannot show the similarity between the both.