Which of the following reactions will yield the crystalline variety of boron?

What is obtained when an aqueous solution of aluminum chloride is heated to dryness?

Identify the correct statement for $B_2H_6$ from those given below.
$(A)$ In $B_2H_6$,all $B-H$ bonds are equivalent.
$(B)$ In $B_2H_6$ there are four $3$-centre-$2$-electron bonds.
$(C)$ $B_2H_6$ is a Lewis acid.
$(D)$ $B_2H_6$ can be synthesized from both $BF_3$ and $NaBH_4$.
$(E)$ $B_2H_6$ is a planar molecule.
Choose the most appropriate answer from the options given below.

An aqueous solution of borax is

Describe the chemical properties of the elements of group $13$.

The Lewis acid character of boron trihalides follows the order: