In the reactions $I$ and $II$,the covalencies of $Be$ and $Al$ in $X$ and $Y$ are respectively:
$I$ $Be(OH)_2 + NaOH \text{ (excess)} \rightarrow X$
$II$ $Al(OH)_3 + NaOH \text{ (excess)} \rightarrow Y$

Orthoboric acid in aqueous medium is

Which of the following statements is not correct about diborane $(B_2H_6)$?

In the structure of $B_2H_6$,the number of $BH_2$ groups present in one plane,and the number of $B-H$ terminal bonds,$B-B$ bonds,and $B-H-B$ bridge bonds are respectively:

When orthoboric acid $(H_3BO_3)$ is subjected to strong heating, the residue left is

Identify the correct statements about the anomalous behaviour of Boron:
$I$. Boron trihalides can form dimeric structures.
$II$. Boron shows $+1$ as a stable oxidation state.
$III$. Maximum covalency of Boron is four.
$IV$. Boron does not form $BF_{6}^{3-}$ ion.