Question

________ acid can decolourise purple colored potassium permanganate solution.

• A. Sulphuric acid
• B. Citric acid
• C. Carbonic acid
• D. Hydrochloric acid

Answer 1

The correct option is B

Citric acid

The explanation for the correct option (B):

• The chemical formula of potassium permanganate is ${\mathrm{KMnO}}_4$ and the solution of ${\mathrm{KMnO}}_4$is purple in color.
• When Citric acid (${\mathrm{C}}_6{\mathrm{H}}_8{\mathrm{O}}_7$) is added to a potassium permanganate solution, the purple-colored solution turns colorless.
• The reaction between ${\mathrm{C}}_6{\mathrm{H}}_8{\mathrm{O}}_7$ and ${\mathrm{KMnO}}_4$, to form Manganese(IV) oxide
  (${\mathrm{MnO}}_2$) and Carbon dioxide (${\text{CO}}_2$), Water (${\mathrm{H}}_2\mathrm{O}$), and Potassium ion (${\mathrm{K}}^{+}$), is:

${\mathrm{C}}_6{\mathrm{H}}_8{\mathrm{O}}_7\left(\mathrm{aq}\right)+6{\mathrm{KMnO}}_4\left(\mathrm{aq}\right)+6{\mathrm{H}}^{+}\left(\mathrm{aq}\right)\to 6{\mathrm{MnO}}_2\left(\mathrm{s}\right)+6{\mathrm{CO}}_2\left(\mathrm{g}\right)+7{\mathrm{H}}_2\mathrm{O}+6{\mathrm{K}}^{+}$

Final Answer: Hence, option (B) is correct. Citric acid can decolorize purple-colored potassium permanganate solution.