The correct order of atomic radii of group $13$ elements is

What are the freezing and boiling points of ammonia $(NH_3)$?

Which of the following hydroxides is acidic?

$STATEMENT-1$: In water,orthoboric acid behaves as a weak monobasic acid. because
$STATEMENT-2$: In water,orthoboric acid acts as a proton donor.

Which of the following statements is correct?

$A$ 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. $H_2SO_4$ is added to a hot solution of $X$,white crystals of an acid $Z$ separate out.
Identify $X, Y$ and $Z$ and write the equations for the reactions.