On heating a mixture of common salt and textK_2textCr_2textO_7 in equal amount along with concentrated textH_2textSO_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: (1) textCrO_2textCl_2 and +5 (2) textCrO_2textCl_2 and +6 (3) textCr_2textO_2textCl_2 and +6 (4) textCr_2textO_2textCl_2 and +3

Solution & Explanation

### Core Logic This is the classic Chromyl Chloride test: 4textNaCl + textK_2textCr_2textO_7 + 6textH_2textSO_4 longrightarrow 2textKHSO_4 + 2textCrO_2textCl_2 + 4textNaHSO_4 + 3textH_2textO In chromyl chloride (textCrO_2textCl_2), chromium is in the +6 oxidation state. ### Step 1: Final Conclusion The gas is textCrO_2textCl_2 and the oxidation state of Cr is +6, corresponding to option (2). ### Pattern Recognition Sees: qualitative analysis test for chloride ions (chromyl chloride test). Trap: Confusing oxidation state of chromium in dichromate versus chromyl chloride. ### Chapter Mix Class 12 Chemistry: p-Block Elements

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