The incorrect statement from the following is:

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

Common alum is

Which statement is correct for $B_2H_6$?

The correct statements from the following are $:$
$(A)$ $Tl^{3+}$ is a powerful oxidising agent
$(B)$ $Al^{3+}$ does not get reduced easily
$(C)$ Both $Al^{3+}$ and $Tl^{3+}$ are very stable in solution
$(D)$ $Tl^{+}$ is more stable than $Tl^{3+}$
$(E)$ $Al^{3+}$ and $Tl^{+}$ are highly stable
Choose the correct answer from the options given below $:$

When an aqueous solution of borax is acidified with hydrochloric acid,a white crystalline solid is formed which is soapy to touch. Is this solid acidic or basic in nature? Explain.