Question

The overall charge present on the cyclic silicate anion $[S{i}_6{O}_{18}{]}^{n-}$ is:

• A. -24
• B. -12
• C. -18
• D. -6

Answer 1

The correct option is B -12

Cyclic silicate : If two oxygen atoms per tetrahedron are shared to form closed rings. The structure with general formula $\left(Si{O}_3^{2-}{)}_n\text{or}\right(Si{O}_3{)}_n^{2n-}$
Comparing cyclic silicate anion $[S{i}_6{O}_{18}{]}^{n-}$ with $(Si{O}_3{)}_n^{2n-}$, n=6.
thus overall charge on cyclic silicate anion = $-2n=-2\times 6=-12$.
Hence correct option is b.