Question

Find the oxidation number of $Pt$ in $[PtC{l}_6{]}^{2-}$ ion.

Answer 1

Let oxidation number of $Pt$ be $x$.
We know that Ox. no. of $Cl=-1$.
So, Ox. no. $Pt$+ 6$(Ox.no.Cl)=-2$
$x+6(-1)=-2$
or $x-6=-2$
or $x=+6-2=+4$
The oxidation number of $Pt$ in $\left[Pt\right(Cl{)}_6{]}^{2-}$ ion is $+4$.