Silicon is an important constituent of which of the following?

Select the member$(s)$ of group $14$ that $(i)$ forms the most acidic dioxide,$(ii)$ is commonly found in $+2$ oxidation state,$(iii)$ used as semiconductor.

Which of the following oxides does not react with $NaOH$ as well as with $HCl$?

Which of the following is an example of a neutral oxide?

Identify the incorrect statement.

Which species does not exist?