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Question Question 4(2014)
Gas Q turns moist lead acetate paper silvery black. Identify Q. pH of R is 10. What kind of substance is R?
The gas Q is H2S (Hydrogen sulphide).
Pb(CH3COO)2 [colourless] + H2S ⟶ PbS [black] + 2CH3COOH
R is an alkaline substance.