Hoop's process is used for the purification of the metal

${H_3}B{O_3}\,\xrightarrow{{{T_1}}}X\,\xrightarrow{{{T_2}}}Y\,\xrightarrow{{\operatorname{Re} d\,\,\,hot}}{B_2}{O_3}$

if $T_1 < T_2$ then $X$ and $Y$ respectively are

In $IIIA$ group, $Tl$ (thalium) shows $+1$ oxidation state while other members show $+3$ oxidation state. Why

In the Hoope's process for refining of aluminium, the fused materials form three different layers and they remain separated during electrolysis also. This is because

Which reactions can be used to prepare diborane

$I.\,\,NaBH_4 + BF_3$ (in ether) $\to $

$II.\,\, NaBH_4 + I_2 \to $

$III.\,\, BF_3 + NaH \to $

Correct order of Lewis Acidic strength?