$TlCl_3$ ની સરખામણીમાં $BCl_3$ ની વધુ સ્થાયીતા તમે કેવી રીતે સમજાવશો ? 

Boron and thallium belong to group $13 $ of the periodic table. In this group, the $+1$ oxidation state becomes more stable on moving down the group. $BCl _{3}$ is more stable than $TlCl _{3}$ because the $+3$ oxidation state of $B$ is more stable than the $+3$ oxidation state of $Tl$. In$Tl$, the $+3$ state is highly oxidising and it reverts back to the more stable $+1$ state.