Salt A commonly used in bakery products on heating gets converted into another salt

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.

Answer:

Baking powder (NaHC03), salt A is commonly used in bakery products. On heating, it forms sodium carbonate (Na2C03), B and C02 gas, C is evolved. When C02 gas is passed through lime water it forms calcium carbonate (CaC03), which is slightly soluble in water making it milky.
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