In the following reaction $2x + B_2H_6 \rightarrow [BH_2x_2]^+ [BH_4]^-$,$x$ is

Colemanite is

Explain the following:
$(1)$ Gallium has higher ionisation enthalpy than aluminum.
$(2)$ Boron does not exist as $B^{3+}$ ion.

In moist air,$AlCl_3$ fumes because:

In the structure of diborane $(B_2H_6)$,the number of $2$-centre-$2$-electron $(2c-2e)$ bonds is $X$ and the number of $3$-centre-$2$-electron $(3c-2e)$ bonds is $Y$. The value of $(X+Y)$ is:

Which of the following chlorides does not react with $PCl_5$ on heating?