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 KMnO_4 solution and reduces Fe^(3+) to Fe^(2+)Identify the solid "A" and the gas "B" and write the reactions involved.

An amorphous solid "A" burns in air to form a gas "B" which turns lime

1.	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 KMnO_4 solution and reduces Fe^(3+) to Fe^(2+)Identify the solid "A" and the gas "B" and write the reactions involved.
Answer» Solution :(A) `S_(8)`, (B) `SO_(2)` with OXYGEN (air), `S_(8)` oxidises to `SO_(2)` `S_(8) + 8O_(2) overset(Delta)to 8SO_(2)` `SO_(2) + Ca(OH)_(2) to CaSO_(3) + H_(2)O` `5SO_(2) + underset("violet")(2MnO_(4)^(-)) + 2H_(2)O to 5SO_(4)^(2-) + 4H^(+) + underset("COLOURLESS") (2MN^(2+))` `2Fe^(3+) + SO_(2) + 2H_(2)O to underset("green")(2Fe^(2+)) + SO_(4)^(2-) + 4H^(+)`