Tiny flakes of silica, $\text{SiO}_2$, are present in some car paints. In the structure of solid $\text{SiO}_2$, • each silicon atom is bonded to $x$ oxygen atoms, • each oxygen atom is bonded to $y$ silicon atoms, • every bond is a $z$ type bond. Which combination of $x$, $y$ and $z$ is correct in this statement?
- A$x=2$, $y=1$, $z=\text{covalent}$
- B$x=2$, $y=1$, $z=\text{ionic}$
- C$x=4$, $y=2$, $z=\text{covalent}$
- D$x=4$, $y=2$, $z=\text{ionic}$