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WBJEE · Chemistry · d and f Block Elements

The orange solid on heating gives a colourless gas and a green solid which can be reduced to metal by aluminium powder. The orange and the green solids are, respectively

  1. A \(\mathrm{NH}_{4} \mathrm{Cr}_{2} \mathrm{O}_{7}\) and \(\mathrm{Cr}_{2} \mathrm{O}_{3}\)
  2. B \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) and \(\mathrm{Cr}_{2} \mathrm{O}_{3}\)
  3. C \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) and \(\mathrm{CrO}_{3}\)
  4. D \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CrO}_{4}\) and \(\mathrm{CrO}_{3}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) and \(\mathrm{Cr}_{2} \mathrm{O}_{3}\)

Step-by-step Solution

Detailed explanation

Orange solid is ammonium dichromate. \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \stackrel{\Delta}{\longrightarrow} \mathrm{N}_{2} \uparrow+\mathrm{Cr}_{2} \mathrm{O}_{3}+4 \mathrm{H}_{2} \mathrm{O}\)…