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JEE Main levelSingle correct optionDifficulty 2 of 3el238

The anionic detergent shown causes persistent foam in rivers. What is the reason?

  1. AThe sulphonate group is hydrolysed to a toxic phenol
  2. BThe straight chain is too short to be degraded
  3. CThe branched alkyl chain resists attack by bacteria, so it is non-biodegradable
  4. DThe compound forms insoluble calcium salts that float

Answer: C

The compound shown is a branched-chain sodium alkylbenzenesulphonate. Microorganisms degrade unbranched chains readily but cannot degrade highly branched ones, so such detergents persist and foam. Its calcium salt is not the cause, and the chain is not straight.
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