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WBJEE · Chemistry · Practical Chemistry

To a solution of a colourless efflorescent sodium salt, when dilute acid is added, a colourless gas is evolved along with formation of a white precipitate. Acidified dichromate solution turns green when the colourless gas is passed through it. The sodium salt is

  1. A \(\mathrm{Na}_{2} \mathrm{SO}_{3}\)
  2. B \(\mathrm{Na}_{2} \mathrm{~S}\)
  3. C \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\)
  4. D \(\mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\)

Step-by-step Solution

Detailed explanation

Hint: \(\underset{\text { (colouriess, efflorescent) }}{\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}(\mathrm{~s})}+2 \mathrm{H}^{+}(\mathrm{dil} .) \rightarrow \mathrm{S}(\mathrm{s})+2 \mathrm{Na}^{+}(\mathrm{aq})+\mathrm{SO}_{2} \uparrow+\mathrm{H}_{2} \mathrm{O}(\ell)\)…