Which of the following halides is least stable and has doubtful existence?

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

Explain the following:
$(1)$ $Tl(NO_3)_3$ acts as an oxidizing agent.
$(2)$ Carbon shows catenation property but lead does not.

How many corners of $SiO_4$ units are shared in the formation of three dimensional silicates?

Which pair of elements can form multiple bonds with itself and oxygen?

Match the following:

List-$I$ (Compound)	List-$II$ (Silicate)
$A$. Zircon $(ZrSiO_4)$	$P$. Ring/Cyclic
$B$. Talc $(Mg_3(OH)_2(Si_2O_5)_2)$	$Q$. Ortho
$C$. Thortveitite $(Sc_2Si_2O_7)$	$R$. Pyro
$D$. Benitoite $(BaTiSi_3O_9)$	$S$. Sheet