$\mathrm{PbO}$ and ${\mathrm{PbO}}_2$ react with $\mathrm{HCl}$ according to following chemical equations:

$2\mathrm{PbO}+4\mathrm{HCl}⟶2{\mathrm{PbCl}}_2+2{\mathrm{H}}_2\mathrm{O}$

${\mathrm{PbO}}_2+4\mathrm{HCl}⟶{\mathrm{PbCl}}_2+{\mathrm{Cl}}_2+2{\mathrm{H}}_2\mathrm{O}$

Why do these compounds differ in their reactivity?

Write balanced chemical equation for the following reactions:

Permanganate ion $\left({{\mathrm{MnO}}_4}^{–}\right)$ reacts with sulphur dioxide gas in acidic medium to produce ${\mathrm{Mn}}^{2+}$ and hydrogensulphate ion. 

(Balance by ion electron method)

Write balanced chemical equation for the following reactions:

Reaction of liquid hydrazine $\left({\mathrm{N}}_2{\mathrm{H}}_4\right)$ with chlorate ion $\left({\mathrm{ClO}}_3^{-}\right)$ in basic medium produces nitric oxide gas and chloride ion in gaseous state. 

(Balance by oxidation number method).

Write balanced chemical equation for the following reactions:

Dichlorine heptaoxide $\left({\mathrm{Cl}}_2{\mathrm{O}}_7\right)$ in gaseous state combines with an aqueous solution of hydrogen peroxide in acidic medium to give chlorite ion $\left({\mathrm{ClO}}_2^{-}\right)$ and oxygen gas.

(Balance by ion electron method)

Calculate the oxidation number of phosphorus in the following species.

${\mathrm{HPO}}_3^{2-}$

Calculate the oxidation number of phosphorus in the following species.

${\mathrm{PO}}_4^{3-}$

Calculate the oxidation number of each sulphur atom in the following compound:

${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$

Calculate the oxidation number of each sulphur atom in the following compounds:

${\mathrm{Na}}_2{\mathrm{S}}_4{\mathrm{O}}_6$