The correct reactions among the following are:

$\mathrm{a}.$ ${\mathrm{MnO}}_4^{-}+{\mathrm{H}}^{+}+{\mathrm{Fe}}^{2+}\to 2{\mathrm{Mn}}^{2+}+{\mathrm{Fe}}^{3+}+{\mathrm{H}}_2\mathrm{O}$
$\mathrm{b}.$ ${\mathrm{C}}_2{\mathrm{O}}_4^{2-}+{\mathrm{MnO}}_4^{-}+{\mathrm{H}}^{+}\to {\mathrm{Mn}}^{2+}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$
$\mathrm{c}.$ ${\mathrm{SO}}_2+{\mathrm{MnO}}_4^{-}+{\mathrm{H}}^{+}\to {\mathrm{Mn}}^{2+}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{SO}}_3$

1. a and c

2. b and c

3. a and b

4. a, b and c

Select the appropriate statement(s) from the following options: 

The correct statement regarding inner transition elements is

The most common oxidation state for lanthanoids and actinoids is:

1. +5

2. -3

3. +1

4. +3

The correct statement(s) about transition elements is/are:  

Which of the following statements is false?  

The $\mathrm{E}°({\mathrm{M}}^{2+}/\mathrm{M})$ value for copper is positive (+0.34 V), because  

The correct trend for I.E₁ (1st Ionization Enthalpy) in the 3d series is: 

The correct statement(s) regarding the oxidation state of transition elements is/are:

The reaction(s) involved in the preparation of potassium dichromate from iron chromite ore is/are: