Question

Which colour change is observed when dilute $\text{HCl}$ is added to a beaker containing copper oxide?

• A. Red colour
• B. Blue-green colour
• C. Purple colour
• D. Orange colour

Answer 1

The correct option is B Blue-green colour

A blue-green colour is observed when dilute $\text{HCl}$ reacts with copper oxide due to the formation of copper chloride.
Copper oxide is a base which reacts with dilute acids to give salt and water. The reaction can be shown as follows:

$CuO+2HCl\to CuC{l}_2+H_{2}O$