Diborane reacts with $HCl$ in the presence of $AlCl_3$ and liberates:

Which one of the following molecular hydrides acts as a Lewis acid?

Which of the following statements is incorrect?

Which of the following is produced by the hydrolysis of diborane $(B_2H_6)$?

Identify the correct statements from the following:
$a$) Borax gives blue coloured $Co(BO_2)_2$ when heated with $Co^{2+}$ salt.
$b$) The correct formula of Borax is $Na_2[B_4O_5(OH)_4] \cdot 8H_2O$.
$c$) Trihalides of boron are Lewis bases.

Orthoboric acid in aqueous medium is