Which of the following statements is true about $H_3BO_3$?

Aluminium chloride exists as a dimer,$Al_2Cl_6$,in the solid state as well as in solutions of non-polar solvents such as benzene. When dissolved in water,it gives:

Hydrated $AlCl_3$ is used as :

Aluminium reacts with dilute $HCl$ and liberates a gas '$A$' and with aqueous alkali liberates a gas '$B$'. $A$ and $B$ respectively are

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 hydroxide is soluble in excess of sodium hydroxide forming the ion