Alumina is insoluble in water because
It is a covalent compound
It has high lattice energy and low heat of hydration
It has low lattice energy and high heat of hydration
$Al^{3+}$ and $O^{2-}$ ions are not excessively hydrated
A nonmetallic element of group $-13$, used in making bullet proof vests is extremely hard solid of black colour. It can exist in many allotropic forms and has unusually high melting point. Its trifluoride acts as Lewis acid towards ammonia. The element exhibits maximum covalence of four. Identify the element and write the reaction of its trifluoride with ammonia. Explain why does the trifluoride acts as a Lewis acid.
Aluminium is a self-preserving metal, because
The structure of diborane contains:
Identify the statement that is not correct as far as structure of diborane is concerned
Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$ : The stability order of +$1$ oxidation state of $\mathrm{Ga}$, In and $\mathrm{Tl}$ is $\mathrm{Ga}<\mathrm{In}<\mathrm{Tl}$.
Reason $R$ : The inert pair effect stabilizes the lower oxidation state down the group.
In the light of the above statements, choose the correct answer from the options given below :