Question

Which among the following is a false statement?

• A. $SiO_{2}$ has a structure similar to that of $CO_{2}$
• B. Natural Si exists only in the combined state
• C. Si can be prepared by reducing $SiO_{2}$ with Mg
• D. Si does not exist in graphite-like structure, but exists only in diamond like structure

Answer 1

Answer: (A)

$SiO_{2}$ has three-dimensional network of $Si-O$ bonds; whilst carbon dioxide consists of discrete $CO_{2}$ molecules . $SiO_{2}$ is solid, whereas $CO_{2}$ is a gas.

B. Because of its great affinity for oxygen, Si always occurs as the oxide, silica $\left(\right.SiO_{2}\left.\right)$ or in the form of silicates, which are the compounds of $SiO_{2}$ with other metal oxides.

C. $SiO_{2}+2Mg \rightarrow Si+2MgO$

D. the reluctance of silicon to form $p\pi -p\pi $ bonds to itself is clearly shown by the fact that silicon does not exists in graphite-like structure, but only in diamond like structure.