Correct statement for $CeO_2$ is/are:
$1$. It is diamagnetic in nature.
$2$. It is a good oxidising agent.
$3$. It is a colourless compound.

When a mixture of manganese dioxide,potassium hydroxide and potassium chlorate is fused,the product obtained is

The transition element of $III-B$ group which forms an alum isomorphic with $Al_2(SO_4)_3 \cdot 18H_2O$ is $Sc$. The color of the compound $Sc_2(SO_4)_3 \cdot (NH_4)_2SO_4 \cdot 24H_2O$ is:

Identify the reactions in which dichromate acts as an oxidising reagent.
$I$. $Cr_2O_7^{2-} + 6Fe^{2+} + 14H^{+} \longrightarrow 2Cr^{3+} + 6Fe^{3+} + 7H_2O$
$II$. $Cr_2O_7^{2-} + 2OH^{-} \longrightarrow 2CrO_4^{2-} + H_2O$
$III$. $Cr_2O_7^{2-} + 6I^{-} + 14H^{+} \longrightarrow 2Cr^{3+} + 3I_2 + 7H_2O$
$IV$. $Na_2Cr_2O_7 + 2KCl \longrightarrow K_2Cr_2O_7 + 2NaCl$

Mention the type of compounds formed when small atoms like $H$,$C$ and $N$ get trapped inside the crystal lattice of transition metals. Also,give the physical and chemical characteristics of these compounds.

The amphoteric oxide of Vanadium $(V)$ is $V_2O_5$. It reacts with alkali to form an oxoion '$X$' and with acid to form an oxoion '$Y$'. The oxidation states of '$V$' in '$X$' and '$Y$' are respectively: