Group 13 Elements: the Boron Family

Aluminium trifluoride is insoluble in anhydrous $\mathrm{HF}$ but dissolves on addition of $\mathrm{NaF}$. Aluminium trifluoride precipitates out of the resulting solution when gaseous ${\mathrm{BF}}_3$ is bubbled through. Give reasons.

If $\mathrm{B}–\mathrm{Cl}$ bond has a dipole moment, explain why ${\mathrm{BCl}}_3$ molecule has zero dipole moment.

Write balanced equations for: $\mathrm{Al} + \mathrm{NaOH} \to$

Consider the compounds, ${\mathrm{BCl}}_3$ and ${\mathrm{CCl}}_4$. How will they behave with water? Justify.

Explain the following reaction when hydrated alumina is treated with aqueous $\mathrm{NaOH}$ solution.

What happens when aluminium is treated with dilute $\mathrm{NaOH}$?

Discuss the pattern of variation in the oxidation states of $\mathrm{C}$ to $\mathrm{Pb}$.
 

When metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of $\mathrm{NaOH}$ to give soluble complex (B). Compound (A) is soluble in dilute $\mathrm{HCl}$ to form compound (C). The compound (A) when heated strongly gives (D), which is used to extract metal. Identify (X), (A), (B), (C) and (D). Write suitable equations to support their identities.

In some of the reactions thallium resembles aluminium, whereas in others it resembles with group $\mathrm{I}$ metals. Support this statement by giving some evidences.

Give the reason, why a mixture of dilute $\mathrm{NaOH}$ and aluminium pieces is used to open drain.

Give the reason why conc. ${\mathrm{HNO}}_3$ can be transported in aluminium container.

Write reactions to justify the amphoteric nature of aluminium.

How can you explain the higher stability of ${\mathrm{BCl}}_3$ as compared to ${\mathrm{TlCl}}_3$?

Discuss the pattern of variation in the oxidation states of $\mathrm{B}$  to $\mathrm{Tl}$ .