The correct order of N-compounds in its decreasing order of oxidation states is :

1. ${\mathrm{HNO}}_3,$ $\mathrm{NO},$ ${\mathrm{N}}_2,$ ${\mathrm{NH}}_4\mathrm{Cl}$

2. ${\mathrm{HNO}}_3,\hspace{0.17em}\mathrm{NO},\hspace{0.17em}{\mathrm{NH}}_4\mathrm{Cl},\hspace{0.17em}{\mathrm{N}}_2$

3. ${\mathrm{HNO}}_3,\hspace{0.17em}{\mathrm{NH}}_4\mathrm{Cl},\hspace{0.17em}\mathrm{NO},\hspace{0.17em}{\mathrm{N}}_2$

4. ${\mathrm{NH}}_4\mathrm{Cl},\hspace{0.17em}{\mathrm{N}}_2,\hspace{0.17em}\mathrm{NO},\hspace{0.17em}{\mathrm{HNO}}_3$

For the redox reaction,
 a${\mathrm{MnO}}_4^{-}+{\mathrm{bC}}_2{\mathrm{O}}_4^{2-}+{\mathrm{cH}}^{+}\to {\mathrm{dMn}}^{2+}+{\mathrm{eCO}}_2+{\mathrm{fH}}_2\mathrm{O}$
the correct stoichiometric coefficients of the reactants a, b, and c respectively for the balanced equation are:

Among the following the correct order of acidity is-

1. HClO < HClO₂< HClO₃< HClO₄
2. HClO₂< HClO < HClO₃< HClO₄
3. HClO₄< HClO₂< HClO < HClO₃
4. HClO₃< HClO₄< HClO₂< HClO