Which one of the following oxides dissolves in both hydrochloric acid and sodium hydroxide?

Which one of the following forms a basic oxide?

Identify the incorrect statement about the group $13$ elements.

Identify the compounds $A$,$X$ and $Z$ in the following reactions :
$A + 2HCl + 5H_2O \to 2NaCl + X$
$X$ $\xrightarrow[370 \ K]{\Delta} HBO_2$ $\xrightarrow[> 370 \ K]{\Delta} Z$

Aluminium $(III)$ chloride forms a dimer because ........

The weakest Lewis acid is