If the number of Silicon atoms is restricted to $23$ only, what would be the number of oxygen atoms and magnitude of negative charges respectively in the structure of Pyroxene (single chain Silicate)?

General formula of chain silicate is  ${\left({\mathrm{SiO}}_3\right)}_{\mathrm{n}}^{2\mathrm{n}-}.$ Number of silicon atom is 23, this depicts that the value of n is 23. The number of oxygen atoms present in pyroxene having 23 silicon atoms is:

$\begin{array}{ccc}\mathrm{Number} \mathrm{of} \mathrm{O} \mathrm{atoms}& =& 3\times \mathrm{n}\\ & =& 3\times 23\\ & =& 69\\ & \cong & 70\end{array}$

Charge on pyroxene is:

$\begin{array}{ccc}\mathrm{charge}& =& 2\times \mathrm{n}\\ & =& 2\times 23\\ & =& 46\end{array}$

Formula of pyroxene is ${\mathrm{S}}_{23}{\mathrm{O}}_{70}^{46-}.$