JEE MAIN - Chemistry (2023 - 24th January Evening Shift - No. 11)

$$\mathrm{K_2Cr_2O_7}$$ paper acidified with dilute $$\mathrm{H_2SO_4}$$ turns green when exposed to :
Sulphur dioxide
Sulphur trioxide
Hydrogen sulphide
Carbon dioxide

Explanation

$\mathrm{SO}_{2}$ gets oxidised in presence of $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ and it converts to $\mathrm{Cr}^{+3}$ in presence of dil. $\mathrm{H}_{2} \mathrm{SO}_{4}$.

Similarly, $\mathrm{H}_{2} \mathrm{~S}$ can also get oxidized to sulphur.

However, most appropriate is (A) Sulphur dioxide.

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