JEE Advanced levelSingle correct optionDifficulty 3 of 3bn053
Assertion (A): In peroxomonosulfuric acid HX2SOX5 (one O−O link) the oxidation number of sulfur is +6 and not +8.
Reason (R): Two of the five oxygen atoms form a peroxo link and are −1 each, so the oxygen total is −8, not −10.
Choose the correct option.
AA is true but R is false
BBoth A and R are true and R is the correct explanation of A
CBoth A and R are true but R is not the correct explanation of A
DA is false but R is true
Answer: B
Hydrogen contributes +2 and the oxygen total is 2(−1)+3(−2)=−8. So 2+x−8=0 and x=+6. If all five O were −2 one would wrongly get +8. Both statements are true and R explains A.