Lead is present in maximum quantity in which of the following types of glass?

$A$ crystalline solid $X$ reacts with dil. $HCl$ to liberate a gas $Y$. $Y$ decolourises acidified $KMnO_4$. When a gas $Z$ is slowly passed into an aqueous solution of $Y$,colloidal sulphur is obtained. $X$ and $Z$ could be,respectively

Which gas is evolved when $SiO_2$ reacts with sodium carbonate?

Identify the incorrect statement about the oxidation states of group $14$ elements.

The hydride of phosphorus is.........

In the following reaction,assign the correct category for the underlined atom based on the product of complete hydrolysis at $R.T.$:
$\underline{Si}F_4 + 2H_2O \longrightarrow H_4SiO_4 + 4HF$