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JEE Main202621 January 2026Evening ShiftChemistryd and f Block ElementsActual

On heating a mixture of common salt and K ₂ Cr ₂ O ₇ in equal amount along with concentrated H ₂ SO ₄ in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas respectively are:

Options

  1. ACr ₂ O ₂ Cl ₂ and +3
  2. BCrO ₂ Cl ₂ and +5
  3. CCrO ₂ Cl ₂ and +6
  4. DCr ₂ O ₂ Cl ₂ and +6

Correct answer

C. CrO ₂ Cl ₂ and +6

Step-by-step solution

When a mixture of NaCl and K2Cr2O7 is heated with concentrated H2SO4, the dichromate ion oxidizes chloride ions. The reaction produces chromyl chloride (CrO2Cl), which is a volatile deep-red colored gas. The dichromate ion contains chromium in the +6 oxidation state. In the reaction, the dichromate is reduced and chloride is oxidized, but the chromium in the product remains in the +6 oxidation state as CrO2Cl (or as CrO2⁺ in ionic form). The gas evolved is CrO2Cl with chromium in the +6 oxidation state

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