Question

In the conversion of $Br_2$ to $BrO^-_3 $, the oxidation number of $Br$ changes from

• A. zero to + 5
• B. + 1 to + 5
• C. zero to -3
• D. +2 to + 5

Answer 1

Answer: (A)

Bromine has zero oxidation state because it is in free state

$B\overset{0}{r_{2}} \to BrO^{-}_{3}$

$\overset{x}{Br}\overset{-2}{O^{-}_{3}}$
$ x + (-2 \times 3 ) = - 1$

$x + (-6) = - 1$

$ x = + 6 -1 $

$= + 5 $

So, oxidation number changes from 0 to +5.