Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which itself is used for removal of hardness of water and a gas ‘C’ is evolved. The gas ‘C’ when passed through lime water, turns it milky. Identify A, B and C. Write chemical equations involved in it.

Salt 'A' is sodium bicarbonate (NaHCO3), commonly known as baking soda. When heated, it decomposes into salt 'B', which is sodium carbonate (Na2CO3), also known as soda ash or washing soda. The gas 'C' evolved in this reaction is carbon dioxide (CO2). When carbon dioxide is passed through lime water (calcium hydroxide solution), it reacts with calcium hydroxide to form calcium carbonate (CaCO3), which is only slightly soluble in water and appears as a milky precipitate.

Here are the chemical equations for each step:

Decomposition of Sodium Bicarbonate (Baking Soda):
2 NaHCO3(s) → Na2CO3(s) + H2O(g) + CO2(g)

Reaction of Carbon Dioxide with Calcium Hydroxide (Lime Water):
CO2(g) + Ca(OH)2(aq) → CaCO3(s) + H2O(l)

So, to summarize:

Salt 'A': Sodium bicarbonate (NaHCO3)
Salt 'B': Sodium carbonate (Na2CO3)
Gas 'C': Carbon dioxide (CO2)