GK
GENERAL SCIENCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The paper has become dusty
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The paper has become very dry
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The paper has reacted with oxygen from the air
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The paper has reacted with pollutants in the air
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Detailed explanation-1: -Detailed Solution. Browning of paper in old books are caused by Oxidation of Celluose. Paper is mainly made up of white cellulose but it also contains lignin present in the wood which when exposed to the air and sunlight turns the paper Yellowish/Brownish.
Detailed explanation-2: -Paper made from wood pulp contains the structural protein lignin which oxidises easily in air. Paper made from wood pulp contains lignin. This is a structural protein that’s responsible for most of the strength of wood. Lignin oxidises quite easily in air to a yellow or brown colour.
Detailed explanation-3: -It’s all thanks to this complex molecule called “lignin.” It’s a dark substance found in wood, and which is responsible for the hardness of the wood. But when the wood is turned into paper, the lignin is retained, and it’s the exposure of lignin to air and sunlight that causes the yellowing you see on your books.
Detailed explanation-4: -It eventually turns paper yellow because of oxidation. Paper is made from wood, which is made up mainly of white cellulose. Wood also has a lot of a dark substance in it called lignin, which ends up in the paper, too, along with the cellulose. The exposure of lignin to air and sunlight is what turns paper yellow.