Redox Reactions And Electrochemistry Ques 356

Question: An element A in a compound ABD has oxidation number $ {{A}^{{{n}^{-}}}} $ . It is oxidised by $ Cr_2O_7^{2-} $ in acid medium. In the experiment $ 1.68\times {{10}^{-3}} $ moles of $ K_2Cr_2O_7 $ was used for $ 3.26\times {{10}^{-3}} $ moles of ABD. The new oxidation number of A after oxidation is:

Options:

A) 3

B) 3-n

C) n-3

D) +n

Show Answer

Answer:

Correct Answer: B

Solution:

[b] Meq. of $ K_2Cr_2O_7=Meq. $ of ABD n-factor of $ K_2Cr_2O_7 $ in acidic medium =6 $ 6\times 1.68\times {{10}^{-3}}=x\times 3.26\times {{10}^{-3}} $ $ x=3 $
$ \Rightarrow $ New oxidation state of $ {{A}^{-n}} $ will be =-n+3



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