Question

In the conversion of $B{r}_2$ to $Br{O}_3^{-}$, 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

$B\stackrel{0}{r_2}\to Br{O}_3^{-}$

$\stackrel{x}{\mathrm{Br}}\stackrel{-2}{O_3^{-}}$
$x+(-2\times 3)=-1$

$x+(-6)=-1$

$x=+6-1$

$=+5$

So, oxidation number changes from 0 to +5.