Question

1. Which of the following oxides will be able to react with hydrochloric acid as well as
with sodium hydroxide to form respective salts ?
(a) CaO
(b) Mgo
(c) Cuo
(d) Al2O3.​

Answer 1

Answer:

CaO is not expected to react with NaOH because NaOH is a base and it can only react with either an acidic oxide or an amphoteric oxide.

Among given options BeO is an amphoteric oxide while B2O3 and SiO2 are acidic oxides.Thus, all of them react with NaOH to form salts.

CaO, on the other hand, is a basic oxide and hence it will not react with NaOH.

Answer 2

Among the following, the oxide which will be able to react with hydrochloric acid as well as  with sodium hydroxide to form respective salts is $\[A{l_2}{O_3}\]$. Thus, the correct option is (d).

Explanation:

• Acidic oxides react with a base to form salts while basic oxides react with acids to form salts.
• Metal oxides are basic oxides, therefore, they react with acids to form salts.
• Non-metal oxides are acidic in nature, therefore, they react with bases to form salts.
• Only amphoteric oxides can react with both acids and bases to form respective salts.
• Among the given oxides, CaO, MgO and CuO are all basic oxides. They will react with sodium hydroxide to give salts but will not react with hydrochloric acid.
• $\[A{l_2}{O_3}\]$ is an amphoteric oxide. It reacts with both acids and bases to form respective salts.
• Therefore, it will react with hydrochloric acid as well as  with sodium hydroxide to form respective salts.