To solve this problem, we need to analyze the stability of the given compounds based on their oxidation states.$\newline$The stability of compounds is often influenced by the oxidation state of the central atom.$\newline$Let's examine each option:$\newline$• Option 1: $TlCl_3 > TlCl \newline$ - Thallium (Tl) can exist in +1 and +3 oxidation states.$\newline$ - The +1 oxidation state is more stable for thallium due to the inert pair effect.$\newline$ - Therefore, TlCl is more stable than TlCl_3.$\newline$• Option 2: $InI_3 > InI \newline$ - Indium (In) can exist in +1 and +3 oxidation states.$\newline$ - The +3 oxidation state is more stable for indium.$\newline$ - Therefore, InI_3 is more stable than InI.$\newline$• Option 3: $AlCl_3 > AlCl \newline$ - Aluminum (Al) typically exists in the +3 oxidation state.$\newline$ - AlCl_3 is the stable form, as AlCl does not exist.$\newline$• Option 4: $TlI > TlI_3 \newline$ - Similar to thallium chloride, thallium iodide (TlI) is more stable than TlI_3 due to the inert pair effect.$\newline$ - The +1 oxidation state is favored for thallium, making TlI more stable.$\newline$Analyzing the options, Option 4 correctly represents the stability relationship:$\newline$• TlI is more stable than TlI$_3. \newline$Therefore, the correct option is Option 4.