Which of the following form dimeric halides
In the following sets of reactants which two sets best exhibit the amphoteric characters of $Al_2O_3. xH_2O$ ?
Set $1$: $Al_2O_3 .xH_2O\, (s)$ and $OH^-(aq)$
Set $2$: $Al_2O_3 .xH_2O\, (s)$ and $H_2O\,(l)$
Set $3$: $Al_2O_3 .xH_2O\, (s)$ and $H^+(aq)$
Set $4$: $Al_2O_3 .xH_2O\, (s)$ and $NH_3(aq)$
Write reactions to justify amphoteric nature of aluminium.
The dissolution of $Al(OH)_3$ by a solution of $NaOH$ results in the formation of
Give industrial preparation for diborane.