How many moles of iodine are liberated when one mol of potassium dichromate reacts with excess of potassium iodide in the presence of concentrated sulphuric acid?

Options

A. 1
B. 2
C. 3
D. 4

Answer

C

Explanation

Bromine has zero oxidation state because it is in free state
`overset(0)(Br_(2)) to BrO_(3)^(0)`
`BrO_(3)^(-)`
`x+(-2 xx 3)=-1`
`x+(-6)=-1`
x=+6-1
x=+5
So, oxidation number changes from 0 to +5