Which of the following is only acidic in nature?

Which of the following is the weakest acid?

Substance $X$ reacts with an aqueous solution of $NaOH$ to form $Y$ and releases $H_2$ gas. When an aqueous solution of $Y$ is heated at $323 \; K - 333 \; K$ and $CO_2$ gas is passed through it,it yields $Al_2O_3 \cdot xH_2O$ (often represented as $Al(OH)_3$) and $Z$. Heating $Z$ at $1200^{\circ}C$ produces $Al_2O_3$. Identify $X, Y,$ and $Z$.

Give important trends and anomalous properties of boron.

The reaction of $H_{3}N_{3}B_{3}Cl_{3}$ $(A)$ with $LiBH_{4}$ in tetrahydrofuran gives inorganic benzene $(B)$. Further,the reaction of $(A)$ with $(C)$ leads to $H_{3}N_{3}B_{3}(Me)_{3}$. Then,compounds $(B)$ and $(C)$ respectively,are

Relative stability orders of $+1$ and $+3$ oxidation states of $Ga, In, Tl$ are respectively: