In diborane $(B_2H_6)$,the two $H-B-H$ bond angles are nearly

Which of the following compounds exhibits acidic nature?

Which of the following is not associated with water molecules?

Give a suitable laboratory preparation method for diborane.

$A$ certain salt $X$ gives the following results:
$(i)$ Its aqueous solution is alkaline to litmus.
$(ii)$ It swells up to a glassy material $Y$ on strong heating.
$(iii)$ When conc. $H_{2}SO_{4}$ is added to a hot solution of $X,$ white crystals of an acid $Z$ separate out.
Write equations for all the above reactions and identify $X, Y,$ and $Z$.

What is the product formed by the action of caustic soda on aluminum hydroxide?