$\begin {array} {1 1} (A)\;\text{Boron compounds act as Lewis acid} \\ (B)\;\text{Boron is a good conductor of electricity } \\ (C)\;\text{Colemanite is one of the chief minerals of boron } \\ (D)\;\text{Boron exists in two isotopic forms $^{10}B$ and $^{11}B$} \end {array}$
