Which one among the following pairs of compound and chemical formula is not correctly matched?
A.Bleaching powder : CaOCl2
B.Soda ash : Na2CO3
C.Baking powder : NaHCl2✓ Correct
D.Plaster of Paris : 2CaSO4·H2O
Explanation
Baking powder/baking soda is sodium bicarbonate with the chemical formula NaHCO3, NOT NaHCl2 (which is not a real compound). Bleaching powder is correctly written as CaOCl2 (calcium oxychloride). Soda ash is sodium carbonate, Na2CO3. Plaster of Paris is calcium sulphate hemihydrate, correctly written as 2CaSO4·H2O (or CaSO4·½H2O). Hence option (c) is the incorrectly matched pair.
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