Q70Long answer
An amorphous solid “A” burns in air to form a gas “B” which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4 solution and reduces Fe3+ to Fe2+. Identify the solid “A” and the gas “B” and write the reactions involved.
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‘A’ is S8 ‘B’ is SO2 gas ∆ → 8SO S8 + 8O2 2 – 2– + 2MnO4 + 5SO2 + 2H2O → 5 SO4 + 4H + 2Mn2+ (violet) (colourless) 2– + 2Fe3+ + SO2 + 2H2O → 2Fe2+ + SO4 + 4H ∆