Name the gas that can readily decolourise acidified KMnO₄ solution.

(1) CO₂           

(2) SO₂           

(3) NO₂             

(4) P₂O₅

A gas that can readily decolorize an acidified KMnO₄ solution is:

1. ${\mathrm{SO}}_2$

2. ${\mathrm{NO}}_2$

3. ${\mathrm{P}}_2{\mathrm{O}}_5$

4. ${\mathrm{CO}}_2$

HgCl₂ and I₂ both, when dissolved in water containing ${\mathrm{I}}^{-}$ ions the pair of species formed is:

1. ${\mathrm{HgI}}_2,$ ${\mathrm{I}}^{-}$

2. ${\mathrm{HgI}}_4^{2-},$ ${\mathrm{I}}_3^{-}$

3. ${\mathrm{Hg}}_2{\mathrm{I}}_2,$ ${\mathrm{I}}^{-}$

4. ${\mathrm{HgI}}_2,$ ${\mathrm{I}}_3^{-}$

SO₂ is passed through an acidified K₂Cr₂O₇ solution.
The correct statement among the following regarding the above experiment is:

1. The solution gets decolorized.

2. SO₂ gets reduced.

3. Green coloured Cr₂(SO₄)₃ gets formed.

4. The solution turns blue.