STD 12 - 5. Co-ordination chemistry — JEE STD 11 Science — Question

Oxidation numbers of $C u:$

$x+4 \times 0-2=0$

$x-2=0$

$x=+2$

(b) Oxidation number of $P t$ in $\left[P t\left(N H_{3}\right)_{2} C l_{2}\right]$ $x+2 \times 0+2 \times-1=0$

$x-2=0$

$x=+2$

(c) Oxidation number of $N i$ in $\left[N i(C O)_{4}\right]$

$x+4 \times 0=0$

$x=0$

(d) Oxidation number of $F e \operatorname{in} K_{3}\left[F e(C N)_{6}\right]$

$3 \times(+1)+x+6 \times-1=0$

$3+x-6=0$

$x=+3$

$\therefore\left[N i(C O)_{4}\right]$ is a zero-valent compound.

Hence, option $C$ is correct.