Chemistry - Complete Pblock- Question with Solution | TestHub

Due to inert pair effect,$\text{Tl}$prefers its$\text{+1}$oxidation state while bonding with iodine and$\text{TlI}$form. Although thallium$\text{(Tl)}$form$\mathrm{T}\mathrm{l}{\mathrm{I}}_3$, but the O.S. of thallium is$\text{+1}$in this compound, because iodine is present as tri-iodide ion$\left({\mathrm{I}}_3^{-}\right).$