Question

Bleaching action of \[S{{O}_{2}}\] is due to:
A) Reduction
B) Oxidation
C) Hydrolysis
D) None of these

Answer 1

Hint: Here bleaching agents are compounds which are used to remove color from substances such as textiles. Bleach is the generic name for any chemical product, which are used industrially and domestically to clean, and to remove stains.

Complete-step- by- step answer:
The decolorizing action of bleaches is due in part to their ability to remove these electrons which are activated by visible light to produce the various colors. Sulphur dioxide and chlorine are used as bleaching agents.
We know that:
i) Reduction: Reduction reaction is a chemical reaction that involves the gaining of electrons by one of the atoms involved in the reaction between two chemicals. And this term is used for the element that accepts electrons, as the oxidation state of the element that gains electrons is lowered.
ii) Oxidation: Oxidation is the process when oxygen combines with an element, changing the appearance of the element.
iii) Hydrolysis: Hydrolysis is a chemical process in which a molecule of water is added to a substance.

Bleaching action can use any of the above three processes. The bleaching action of \[S{{O}_{2}}\]is due to the reduction. Sulphur dioxide is used as a bleaching agent as it removes oxygen from the coloured substances and makes it colorless. The colour of pigment on exposure to SO2 gets reduced to a colourless compound. Reaction of bleaching action:
\[S{{O}_{2}}+2{{H}_{2}}O\to {{H}_{2}}S{{O}_{4}}+2\underset{nascent}{\mathop{[H]}}\,\]
So, from the above explanation we can say that the bleaching action of \[S{{O}_{2}}\]is due to the reduction.

Then the correct option is “A”.

Note: Atmospheric oxygen slowly occupies removed oxygen and the material regains the color. Chlorine is also a bleaching agent and its bleaching action is based on oxidation.