Which of the following on hydrolysis produces diborane $(B_2H_6)$?

Write balanced equations for :
$(i) \, BF_{3} + LiH \to $
$(ii) \, B_{2}H_{6} + H_{2}O \to $
$(iii) \, NaH + B_{2}H_{6} \to $
$(iv) \, H_{3}BO_{3} \xrightarrow{\Delta }$
$(v) \, Al + NaOH \to $
$(vi) \, B_{2}H_{6} + NH_{3} \to $

Discuss the pattern of variation in the oxidation states of $(i)$ $B$ to $Tl$ and $(ii)$ $C$ to $Pb$.

Which of the following elements is used in thermometry at high temperatures?

Which of the following statements is incorrect?

In group $13$ of the long form of the periodic table,an element $X$ has a boiling point of $T_2 \ (K)$ and a melting point of $T_1 \ (K)$. Identify the element $X$ for which $T_2 - T_1 \ (K)$ is maximum.