Which of the following oxides is amphoteric in nature?

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

$A$ 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.

In the following reaction,assign the correct category for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{I}Cl_3 + H_2O \longrightarrow HIO_2 + HCl$

Which of the following statements is incorrect?

Match the species given in Column-$I$ with properties given in Column-$II$.

Column-$I$	Column-$II$
$A$. Diborane	$1$. Used as a flux for soldering metals
$B$. Gallium	$2$. Crystalline form of silica
$C$. Borax	$3$. Banana bonds
$D$. Alumino silicate	$4$. Low melting,high boiling,useful for measuring high temperatures
$E$. Quartz	$5$. Used as catalyst in petrochemical industries