How is soap made?

Answer and explanation

Correct answer: C. By heating a fat or oil with sodium hydroxide solution

  1. Step 1: A fat or oil is hydrolysed by an alkali.
  2. Step 2: This gives glycerol and the sodium salts of the fatty acids, which are soap.
Answer
By heating a fat or oil with sodium hydroxide solution.
Why not the others: By heating a fat with hydrochloric acid: soap needs an alkali. By cooling an alkane in water: this does not give soap. By burning a fat in oxygen: combustion destroys the fat.

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