Red lead is

Which of the following statements is correct with respect to the property of elements with an increase in atomic number in the carbon family (group $14$)?

$A$ 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

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{C}Cl_4 + H_2O \longrightarrow \text{No reaction}$

Which of the following elements exhibit metallic nature among $C$,$Si$,$Ge$,$Sn$,and $Pb$?

Give reasons: Diamond is used as an abrasive.