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 substances imparts a green color to the burner flame?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2Na[Al(OH)_4] + CO_2 \longrightarrow 2Al(OH)_3 \downarrow + Na_2CO_3$

In the following reaction,assign the state for the underlined atom for the product of complete hydrolysis at $R.T.$:
$H_4\underline{B}_2O_6 + H_2O \longrightarrow H_3BO_3 + H_2O_2$

What happens when:
$(a)$ Borax is heated strongly,
$(b)$ Boric acid is added to water,
$(c)$ Aluminium is treated with dilute $NaOH$,
$(d)$ $BF_{3}$ is reacted with ammonia?

Boron trifluoride on reaction with lithium aluminium hydride in ether gives $LiF$,$AlF_3$ and $X$. $X$ on reaction with $NH_3$ gives $Y$. $Y$ on further heating gives a compound $Z$. The number of $\sigma$-bonds and $\pi$-bonds in $Z$ are $x$ and $y$ respectively. $(x+y)$ is equal to