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.

<p><span data-teams="true">This is a long answer type question as classified in NCERT Exemplar</span></p><p>‘A’ is S₈ ‘B’ is SO₂ gas</p><p>&nbsp;S₈ + 8O₂<img src="https://images.shiksha.com/mediadata/images/articles/1746003447phpVr2cyI.jpeg" alt="" width="37" height="21"> 8SO₂</p><p>2MnO₄ ^– + 5SO₂ + 2H₂O → 5 SO₄^2– + 4H⁺ + 2Mn²⁺</p><p>(violet)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (colourless)</p><p>2Fe³⁺+ SO₂ + 2H₂O → 2Fe²⁺ + SO₄^2– + 4H⁺</p>

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