question_answer

Oxidation number of Cr in \[Cr{{O}_{6}}\] is

A)  +8                                         

B)  +6

C)  +4                                         

D)  +10

Correct Answer: B

Solution :

                 Key Idea The structure of \[Cr{{O}_{5}}\] is                 In \[Cr{{O}_{5}}\] four oxygen atoms are present as peroxide (oxidation number-1) while the fifth is present as oxide (oxidation number -2 ).                 Let the oxidation number of Cr is x in \[Cr{{O}_{5}}\]. \[\therefore \]  \[x+4(-1)+1(-2)=0\]                 \[x-4-2=0\]                 \[x=+6\]