Question

what is oxidation state of hg in hg co (scn)_4​

Answer 1

Here Hg is in +2 state and NCS i.e thiocyanate is in -1.The complex gives -2 charge on the cordination sphere.

So ,let the oxidation state of Co be x.

Therefore in Hg[Co(NCS)4]^-2

x+4(-1)=-2

X=-2+4

X=+2

If here Hg would have been in +3state then cordination number of Cobalt would have been

X+4(-)=+3

X=-3+4

X=+1

That's all

Thankyou.