In order to concentrate galena (which contains ZnS as impurity) by froth-floatation process, sodium cyanide is used as depressant. NaCN dissolves ZnS due to formation of water soluble complex(A). Find wxyz, 

where $\mathrm{w}$ = coordination number of central metaion. in complex ion of (A)

$\mathrm{x}$ = number of unpaired electrons in (A)

$\mathrm{y}$ = total number of possible linkage isomers of (A) including (A)

$\mathrm{z}$ = maximum number of atoms in a single plane in the complex ion of {A)

The reaction and complex formed is :

$\mathrm{A}\to {\mathrm{Na}}_2\underset{\left({\mathrm{sp}}^3\right)}{\left[\mathrm{Zn}(\mathrm{CN}{)}_4\right]};$

It is a tetrahedral compound of zinc that is seen above. $\mathrm{Zn}$ has an oxidation state of +2 and a coordination number of 4. As a result, it has no unpaired electrons and a $3{\mathrm{d}}^{10}4{\mathrm{s}}^0$ configuration.
Cyanide, symbol $\mathrm{CN}$, is an ambidentate ligand. Both the C end and the N end can connect together to form a bond. Therefore, there will be five potential connection isomers.
One plane can include up to five atoms, so take the plane that passes through the two atoms of $\mathrm{CN}$ (which are in the plane) and the central atom $\mathrm{Zn}$ as an example.

So,

$\mathrm{w}=4,$$\mathrm{x}=0,\mathrm{y}=5,\mathrm{z}=5$

Hence, $\mathrm{W}+\mathrm{x}+\mathrm{y}+\mathrm{z}=14$