A group $13$ element $'X'$  reacts with chlorine gas to produce a compound  $XCl_3. XCl_3$ is electron deficient and easily reacts with $NH_3$ to form $Cl_3X \leftarrow NH_3$ adduct, however, $XCl_3$ does not dimerize. $X$  is

Which one of the following statements is not true regarding diborane ?

Correct Lewis acidity order of $BX_3$ is

The correct statements from the following are :

$(A)$ The decreasing order of atomic radii of group $13$ elements is $\mathrm{Tl}>\mathrm{In}>\mathrm{Ga}>\mathrm{Al}>\mathrm{B}$.

$(B)$ Down the group $13$ electronegativity decreases from top to bottom.

$(C)$ $\mathrm{Al}$ dissolves in dil. $\mathrm{HCl}$ and liberate $\mathrm{H}_2$ but conc. $\mathrm{HNO}_3$ renders Al passive by forming a protective oxide layer on the surface.

$(D)$ All elements of group 13 exhibits highly stable +1 oxidation state.

$(E)$ Hybridisation of $\mathrm{Al}$ in $\left[\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$ ion is $\mathrm{sp}^3 \mathrm{~d}^2$.

Choose the correct answer from the options given below:

The correct statements among $I$ to $III$ regarding group $13$ element oxides are,

$I$. Boron trioxide is acidic

$II$. Oxides of aluminium and gallium are amphoteric

$III$. Oxides of indium and thallium are basic