Boron compounds act as Lewis acids due to their .....

Which of the following is the strongest Lewis acid?

Aluminium is not used:

The correct statements from the following are:
$(A)$ Ionic radii of trivalent cations of group $13$ elements decrease down the group.
$(B)$ Electronegativity of group $13$ elements decreases down the group.
$(C)$ Among the group $13$ elements, Boron has the highest first ionisation enthalpy.
$(D)$ The trichlorides and triiodides of group $13$ elements are covalent in nature.
Choose the correct answer from the options given below:

The chemical name of borax is

Write the preparation of diborane and describe its physical and chemical properties.