Question

The substance which causes paper to discolour is:

• A. acid.
• B. linen.
• C. lignin.
• D. preservatives.

Hint:

When a passage specifies a cause for a particular effect (e.g., discolouration), use that exact term in your answer — even if other factors contribute to related deterioration.

Answer 1

The Correct Option is C

The passage clearly states that paper made from mechanically ground wood pulp contains lignin, which is a major factor causing paper to discolour and eventually disintegrate.
Lignin is a natural component of wood that reacts with light and oxygen, leading to yellowing and brittleness.
Option (a) acid — while acidity contributes to instability and deterioration, the passage specifically links discolouration to lignin.
Option (b) linen — is a durable fiber used in older, long-lasting papers, and does not cause discolouration.
Option (d) preservatives — are not mentioned as a factor in deterioration in the passage.
Thus, (c) is the correct answer because lignin is directly identified as the cause of paper discolouration.