$AlF_3$ is soluble in $HF$ only in presence of $KF.$ It is due to the formation of

In some of the reactions thallium resembles aluminium, whereas in others it resembles with group $1$ metals. Support this statement by giving some evidences.

Boron form covalent compound due to

How would you explain the lower atomic radius of $Ga$ as compared to $Al$?

When metal $X$ is treated with sodium hydroxide, a white precipitate $(A)$ is obtained, which  is soluble in excess of $NaOH$ to give soluble complex $(B)$. Compound $(A)$ is soluble in dilute $HCl$ 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.

Give reasons:

$(i)$ Conc. $HNO _{3}$ can be transported in aluminium container.

$(ii)$ $A$ mixture of dilute $NaOH$ and aluminium pieces is used to open drain.

$(iii)$ Graphite is used as lubricant.

$(iv)$ Diamond is used as an abrasive.

$(v)$ Aluminium alloys are used to make aircraft body.

$(vi)$ Aluminium utensils should not be kept in water overnight.

$(vii)$ Aluminium wire is used to make transmission cables.