If `[PtCl_6]^(x-)` follows the Sidgwick rule of stability, what is the oxidation state of Pt and complex ?

Explanation

`[PtCl_(6)]^(x-)` following Sidgwick rule of stability, thus EAN of Pt is to be equal to the atomic number of nearest inert gas 86(Rn).
Let the oxidation state of platinum in `[PtCl_(6)]^(x-)` complex ion is y
`y+6(-1)=-x (or) y =6-x`
`86=78-(6-x)+2xx6=78-6+x+12 , x=2`
Oxidation state of platinum forming the complex `=6-x=6-2=+4`
Oxidation state of the complex `=-2`.