2023 · Q32
Which of the following statements with regard to the reaction given below are corrct? CaO(s) + H2O(l) -> Ca(OH)2(aq) + Heat
- 1Quicklime is used for white-washing of walls.
- 2The solution of slaked lime is used for whitewashing of walls.
- 3CaO reacts slowly with CO2 in air to form a thin layer of CaCO3 on walls.
- 4Calcium hydroxide called 'slaked lime' is an inorganic compound.
Select the correct answer using the code given below.
General KnowledgeChemistry
- A1 and 4 only
- B2 and 4
- C2 and 3
- D1, 3 and 4
Explanation
Statement 2 is true: a solution of slaked lime (calcium hydroxide) in water is used for whitewashing walls. Statement 4 is true: slaked lime, Ca(OH)2, is an inorganic compound. Statement 1 is false: quicklime (CaO) itself is not used for whitewashing — it is first slaked with water to make the whitewash. Statement 3 is false: it is calcium hydroxide (not CaO) that reacts slowly with atmospheric CO2 to form the thin CaCO3 layer. Hence only statements 2 and 4 are correct.