Which of the following statements with regard to the reaction CaO(s) + H2O(l) -> Ca(OH)2(aq) + Heat are correct? 1. Quicklime is used for white-washing of walls. 2. The solution of slaked lime is used for whitewashing of walls. 3. CaO reacts slowly with CO2 in air to form a thin layer of CaCO3 on walls. 4. Calcium hydroxide, called ‘slaked lime’, is an inorganic compound.