Covalent electron deficient hydride is formed by

The correct formula of borax is

The correct statements from the following are :

$(A)$ The decreasing order of atomic radii of group $13$ elements is $\mathrm{Tl}>\mathrm{In}>\mathrm{Ga}>\mathrm{Al}>\mathrm{B}$.

$(B)$ Down the group $13$ electronegativity decreases from top to bottom.

$(C)$ $\mathrm{Al}$ dissolves in dil. $\mathrm{HCl}$ and liberate $\mathrm{H}_2$ but conc. $\mathrm{HNO}_3$ renders Al passive by forming a protective oxide layer on the surface.

$(D)$ All elements of group 13 exhibits highly stable +1 oxidation state.

$(E)$ Hybridisation of $\mathrm{Al}$ in $\left[\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$ ion is $\mathrm{sp}^3 \mathrm{~d}^2$.

Choose the correct answer from the options given below:

${H_3}B{O_3} + {H_2}O_2 \to {H_2}O + 'X' {\xrightarrow{{NAOH}} }{'Y'}$

Which of the following statements is $/$ are Correct for $'Y'$

Suggest reasons why the $B-F$ bond lengths in $BF_3\, (130\, pm)$ and $BF_4^- \,(143\, pm)$ differ. 

The number of neutrons present in the more abundant isotope of boron is ' $\mathrm{x}$ '. Amorphous boron upon heating with air forms a product, in which the oxidation state of boron is ' $y$ '. The value of $x+y$ is ...