A) 0
B) 5
C) 7
D) 9
Correct Answer: A
Solution :
Key Idea: The sum of oxidation state of all elements in a compound is always zero. Let oxidation state of Cr in \[{{K}_{2}}C{{r}_{2}}{{O}_{7}}=x\] \[(+1\times 2)+2x+(-2\times 7)=0\] or \[+2+2x-14=0\] \[\therefore \] \[x=+6\] Let oxidation sate of Cr in \[{{K}_{2}}Cr{{O}_{4}}=x\] \[+1\times 2+x+(-2\times 7)=0\] \[2+x-8=0\] \[x=6\] \[\therefore \]Change in oxidation state of Cr is zero when it changes from\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\]to\[{{K}_{2}}Cr{{O}_{4}}\]You need to login to perform this action.
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