Aluminium becomes passive in:

Aluminium becomes passive in all of these.On addition of strong acids like Nitric acid,chromic acid and per- chloric acid it is converted to alumina. Since, it forms a protective oxide layer over it and can prevent the fur- ther attack of acid. Therefore, aluminium containers are safer to store nitric acid. Passage (Ques. 25 to 29) Fused 2 6 11 2 3 3 Ca B O Na CO (A) (B) CaCO + ¾¾¾® + + 2 2 3 Solution (A) CO (B) Na CO + ¾¾® + 2 H O (B) Conc.HCl NaCl Acid Acid(C) + ¾¾® + ¾¾¾ ® Strongly heated (C) (D) ¾¾¾® Heated 4 inflame (D) CuSO Blue coloured (E) compound + ¾¾¾®