KVPY2018ChemistryRedox Reactions
The formal oxidation numbers of C r and C l in the ions Cr 2 O 7 2 - and C l O 3 - , respectively are
Options
- A  + 6   and   + 7
- B+ 7   and   + 5
- C+ 6   and   + 5
- D+ 8   and   + 7
Correct answer
C. + 6   and   + 5
Step-by-step solution
In C r 2 O 7 2 - Let the oxidation state of C r be x ∴    2 x + 7 - 2 = - 2 2   x - 14 = - 2 2   x = 12 x = + 6 In C l O 3 - Let the oxidation state of C l be x ∴    1 x + 3 - 2 = - 1 x - 6 = - 1 x = + 5