$A$ group $13$ element '$X$' reacts with chlorine gas to produce a compound $XCl_3$. $XCl_3$ is electron deficient and easily reacts with $NH_3$ to form $Cl_3X \leftarrow NH_3$ adduct,however,$XCl_3$ does not dimerize. $X$ is

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

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?

Draw the structure of diborene $(B_2H_4)$.

How would you explain the lower atomic radius of $Ga$ as compared to $Al$?

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$ : The stability order of $+1$ oxidation state of $Ga$,$In$ and $Tl$ is $Ga < In < Tl$.
Reason $R$ : The inert pair effect stabilizes the lower oxidation state down the group.
In the light of the above statements,choose the correct answer from the options given below :