The densities of boron family elements are more than

Given below are two statements:

Statement I: Boron is extremely hard indicating its high lattice energy.

Statement II: Boron has highest melting and boiling point compared to its other group members.

In the light of the above statements, choose the most appropriate answer from the options given below

Given below are two statements:
Statement $\mathrm{I}:$ Colourless cupric metaborate is reduced to cuprous metaborate in a luminous flame.

Statement $\mathrm{II}:$ Cuprous metaborate is obtained by heating boric anhydride and copper sulphate in a non-luminous flame.

In the light of the above statements, choose the most appropriate answer from the options given below.

Given below are two statements:

Statement I: The decrease in first ionization enthalpy from $\mathrm{B}$ to $\mathrm{Al}$ is much larger than that from $\mathrm{Al}$ to $\mathrm{Ga}$.

Statement II: The d orbitals in $\mathrm{Ga}$ are completely filled.

In the light of the above statements, choose the most appropriate answer from the options given below

Given below are two statements: one is labelled as Assertion $\mathrm{A}$ and the other is labelled as Reason $\mathrm{R}$.

Assertion $\mathrm{A}:$ In $\mathrm{T}l{\mathrm{I}}_3,$ isomorphous to ${\mathrm{CsI}}_3$, the metal is present in $+1$ oxidation state.

Reason $\mathrm{R}:$ $\mathrm{T}l$ metal has fourteen $\mathrm{f}$ electrons in its electronic configuration.

In the light of the above statements, choose the most appropriate answer from the options given below: