Substance X used for whitewashing

A typical lime whitewash.

A solution of a substance ‘X’ is used for whitewashing.

  1. Name the substance “X’ and write its formula.
  2. Write the reaction of the substance ‘X’ named above with water.


  1. Substance X in the question is Calcium oxide or “Quick lime”.
  2. Calcium oxide (AKA slaked lime) reacts with water and forms calcium hydroxide and releases energy as heat.

Application: When we apply slaked lime to walls of building as a thin layer. Within 2 to 3 days, it reacts to atmospheric carbon dioxide to form calcium carbonate. Calcium carbonate is hard and shiny, so it protects the wall from harsh weather and also looks appealing.

Ca(OH2) aq. + CO2(g)  ————> CaCO3  +   H2O(l)

Next: Why is the amount of gas collected in one of the test tubes during hydrolysis of water id double than the other.

See also: Other solved questions from chapter 1.

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