Redox Reactions And Electrochemistry Ques 423

Question: The oxidation number of $ Cr $ in $ K_2Cr_2O_7 $ is [CPMT 1981, 85, 90, 93, 99; KCET 1992; BHU 1988, 98; AFMC 1991, 99; EAMCET 1986; MP PMT 1996, 99, 2002; MP PET/PMT 1998; Bihar CEE 1995; RPET 2000]

Options:

A) +6

B) - 7

C) +2

D) - 2

Show Answer

Answer:

Correct Answer: A

Solution:

$ \overset{*}{\mathop{K_2Cr_2O_7}}, $ $ 2+2x-2\times 7=0 $ ; $ 2x-14+2=0 $ $ 2x=12 $ ; $ x=\frac{12}{2}=+6 $ .



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