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NEET2026ChemistryChapterActual

An inorganic reaction sequence involving potassium dichromate is shown in the given flowchart. Identify the chemical formula of the reddish-brown gas (X), the yellow precipitate (Z), and the oxidation state of the transition metal in gas (X).

Options

  1. AX = CrO ₂ Cl ₂ , Z = PbCrO ₄ , Oxidation state = +6
  2. BX = CrCl ₃ , Z = PbCrO ₄ , Oxidation state = +3
  3. CX = CrO ₂ Cl ₂ , Z = PbCr ₂ O ₇ , Oxidation state = +6
  4. DX = CrO ₃ , Z = PbCr ₂ O ₇ , Oxidation state = +6

Correct answer

A. X = CrO ₂ Cl ₂ , Z = PbCrO ₄ , Oxidation state = +6

Step-by-step solution

The given reaction sequence is the chromyl chloride test for chloride ions. Reaction 1: Heating K ₂ Cr ₂ O ₇ with NaCl and conc. H ₂ SO ₄ produces reddish-brown vapors of chromyl chloride. K ₂ Cr ₂ O ₇ + 4 NaCl + 6 H ₂ SO ₄ 2 KHSO ₄ + 4 NaHSO ₄ + 2 CrO ₂ Cl ₂ + 3 H ₂ O Gas (X) is CrO ₂ Cl ₂ . Reaction 2: Passing CrO ₂ Cl ₂ gas into aqueous NaOH gives a yellow solution of sodium chromate. CrO ₂ Cl ₂ + 4 NaOH Na ₂ CrO ₄ + 2 NaCl + 2 H ₂ O Solution (Y) contains Na ₂ CrO ₄ . Reaction 3: Adding lead acetate to the yello

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