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

(N/A) Due to the inert pair effect,$Tl$ is more stable in the $+1$ oxidation state than in the $+3$ oxidation state. Therefore,$Tl(NO_3)_3$ acts as a strong oxidizing agent.
Carbon atoms have the tendency to link with one another through covalent bonds to form chains and rings. This property is called catenation. This is because $C-C$ bonds are very strong. Down the group,the atomic size increases and electronegativity decreases,and thereby,the tendency to show catenation decreases. This can be clearly seen from bond enthalpy values. The order of catenation is $C \gg Si > Ge \approx Sn$. Lead does not show catenation.