Identify the correct statements from the following:
$(a)$ In orthoboric acid, boron is in planar geometry.
$(b)$ In $BCl_3 \cdot NH_3$, boron has tetrahedral geometry.
$(c)$ Aqueous solution of borax is acidic.

What are the correct statements about the elements of group $13$ given below?
$(I)$ The stability of $+1$ oxidation state follows the order $Tl > In > Ga$
$(II)$ Boron has the lowest melting point and boiling point as it is a non-metal
$(III)$ Boron shows a maximum covalency of $4$ in its compounds
$(IV)$ The order of atomic radius is $Ga > Al > In$
$(V)$ Aluminium is passive to concentrated nitric acid

Colemanite is

In borax, the number of $B-O-B$ links and $B-OH$ bonds present are, respectively:

Which one of the following is the correct statement?

In which of the following molecules is a hydrogen bridge bond present?