Question

Which of the following brings about dry bleaching?
(A) Ozone
(B) Chlorine
(C) Sulphur dioxide
(D) Hydrogen peroxide

Answer 1

Hint: To solve this question you must know about bleaching. Bleaching is a process to remove stains from fabric or any cloth material. Bleaching is done on the basis of the oxidation and reduction properties of certain bleaching agents.

Complete step by step solution:
Dry bleaching is done in the absence of water. As we know bleaching is the process of removal of stains. Ozone is used as a dry bleaching agent.
Ozone on decomposition gives nascent oxygen So it acts as a bleaching agent. Nascent oxygen is a single molecule of oxygen that is not bonded to any other molecule.
\[{O_3}\xrightarrow{{}}{O_2} + [O]\]
Hydrogen peroxide and chlorine compounds such as sodium chlorite, chloramine etc. also act as bleaching agents but in the presence of water.

Hence the correct option is (A).

Note: Hydrogen peroxide is also used as a bleaching agent. Hydrogen peroxide decomposes in water to form hydrogen ion and per hydroxyl ion. Perhydroxyl ion acts as an active bleaching agent. It is mainly used in the bleaching of cotton and synthetic fabrics.
\[{H_2}{O_2} + {H_2}O\xrightarrow{{}}{H^ + } + HO{O^ - }\]