Marine plants are an important source of which of the following?

Which of the following represents the structure of inorganic benzene?

$A$ compound $(A)$ of boron reacts with $NMe_3$ to give an adduct $(B)$ which on hydrolysis gives a compound $(C)$ and hydrogen gas. Compound $(C)$ is an acid. Identify the compounds $A, B$ and $C$. Give the reactions involved.

Hydrated $AlCl_3$ is used as :

Group-$13$ elements react with $O_2$ to form oxides of the type $M_2O_3$ ($M =$ element). Which among the following is the most basic oxide?

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 $Z$.