Question

A metal $M$ does not liberate hydrogen from acids but reacts with oxygen to give a black coloured product. Identify the black coloured product:

• A. $MgO$
• B. $CuO$
• C. $FeO$
• D. $ZnO$

Answer 1

Answer: (B)

$CuO$

The metal $M$ is copper $\left(Cu\right)$ which reacts with oxygen when heated in the air to form black coloured copper(ll) oxide. The reaction can be written as:

$2Cu+O_2\to 2CuO$

Copper is present below hydrogen in the reactivity series of metals. So, it does not react with dilute acids like hydrochloric acid or sulfuric acid.