An element A in a compound ABD has an oxidation number A–n. It is oxidized by Cr2O7 2–in acidic medium. In an experiment 1.68 × 10–3mol of K2Cr2O7was required for 3.26 × 10–3mol of the compound ABD. Calculate new oxidation state of A. (1) 3 – n (2) n + 3 (3) –3 (4) +n

Dear ​Utkarsh Kaushik,

Equivalent of Cr2O72- = Equivalent of ABD or A-nmole×valency factor=mole×valency factorin acidic medium Cr2O72-  changes to Cr3+ hence n-factor or valency factro is 6 (change in oxi. no is 3 per atom)so n-factor for A can be calculated1.68×10-3×6=3.26×10-3×n-factorn-factor=3so A-n will be oxidized so oxidation no. increase from n to 3-n.Option 1 is correct.

Regards

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