Question

The inactiveness of aluminium in the presence of conc. $HN{O}_3$ is due to the formation of a layer of :

• A. $AlN$
• B. $A{l}_2{S}_3$
• C. $A{l}_4{C}_3$
• D. $A{l}_2{O}_3$

Answer 1

The correct option is D $A{l}_2{O}_3$

A passive layer of aluminium oxide is formed by the reaction of aluminium with concentrated nitric acid.

$2Al+6\underset{conc.}{HN{O}_3}\to A{l}_2{O}_3+6N{O}_2+3H_{2}O$

Therefore, option D is correct.