Explain the following:

Boron does not form ${\mathrm{B}}^{3+}$ ion.

Explain the following:

${\mathrm{AlCl}}_3$ forms a dimer but ${\mathrm{BCl}}_3$ does not form dimer.

Explain the following:

Boron and aluminium halides behave as Lewis acids.

Explain the following:

Aluminium is stable in air and water.

Explain the following:

No visible reaction occurs when aluminium is left in contact concentrated nitric acid.

Explain the following:

Aluminium containers can be used to store concentrated ${\mathrm{HNO}}_3$.

Explain the following:

Aluminium vessel should not be cleaned with cleaning agent containing washing soda.

Explain the following:

Aluminium metal is frequently used as reducing agent for the extraction of metals such as $\mathrm{Cr}, \mathrm{Mn}, \mathrm{Fe}$, etc.

Explain the following:

The hydroxides of aluminium and iron are insoluble in water. However, $\mathrm{NaOH}$ is used to separate from one from the other.