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JEE Main 2020 — Electrochemistry Question with Solution

JEE Main 2020 (03 Sep Shift 2)

Question

An acidic solution of dichromate is electrolyzed for 8 minutes using 2 A current. As per the following equation

Cr2O72+14H++6e-→2Cr3++7H2O
The amount of Cr3+. obtained was 0.104g. The efficiency of the process (in%) is (Take : F=960000C, At. mass of chromium =52)

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Show full solutionCorrect answer: 60
Correct answer
60

Step-by-step explanation

Charge q=it=2×8×60=960 C

96096000=0.01F

Cr2O72-+14H++6e- →  2Cr3+ + 7H2O

0.01F   13×0.01 mole

Theoritical mass of Cr3+=13×60096000×52=0.173g

So, efficiency =WactualWTheoritial×100=0.1040.173×100=60%

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About this question

This is a previous-year question from JEE Main 2020, covering the Electrochemistry chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.