The reaction of $\mathrm{H}_{3} \mathrm{N}_{3} \mathrm{B}_{3} \mathrm{Cl}_{3}$ $(A)$ with $\mathrm{LiBH}_{4}$ in tetrahydrofurane gives inorganic benzene $(B)$. Further, the reaction of $(A)$ with $(C)$ leads to $\mathrm{H}_{3} \mathrm{N}_{3} \mathrm{B}_{3}(\mathrm{Me})_{3}$. than Compounds $(\mathrm{B})$ and $(\mathrm{C})$ respectively, are

Correct Lewis acidity order of $BX_3$ is

Write preparation of diborane and give physical and chemical properties of it.

Give structure of gaseous $AlCl_3$. 

Heating an aqueous solution of aluminium chloride to dryness will give