Which of the following reaction involves oxidation reduction?

Options

A. `H_(2)+Br_(2)to 2HBr`
B. `NaBr+HCl to NaCl+HBr`
C. `HBr+AgNO_(3) to AgBr+HNO_(3)`
D. `2NaOH+H_(2)SO_(4) to Na_(2)SO_(4)+2H_(2)O`

Answer

A

Explanation

Oxidation state of I in `IO_(3)^(-)`
x+(-2) 3=-1 `rArr x=+5`
Oxidation state of I in `IO_(4)^(-)`
`x+(-2)4=-1 rArr x=+7`
Oxidation state of I in KI
+1 +x=0 `rArr x=-1`
oxidation state of I in `I_(2)`
x=0
Hence, the oxidation number of iodine in `IO_(3)^(-), IO_(4)^(-), KI and I_(2)` are respectively +5, +7, -1 and 0