Question

A shiny - brown substance X on heating in air turns black and a new compound Y is formed. Name the substance X and black compound Y.

• A. X = Fe and Y = FeO
• B. X = Cu and Y = Cu(OH)₂
• C. X = Cu and Y = CuO
• D. X = Al and Y = AlO₃

Answer 1

The correct option is C

X = Cu and Y = CuO

Explanation:

• The brown coloured metal is copper. Hence ′X′ is copper.
• Copper burned in the presence of oxygen and turns into black copper oxide.
• The balanced chemical reaction can be written as:
• $\underset{\mathrm{Copper}}{2\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Copper}\mathrm{oxide}}{2\mathrm{CuO}\left(\mathrm{s}\right)}$
• Since copper gains oxygen. So, in this reaction copper undergo oxidation.

Therefore, option (C) is correct.