The correct set of ions (aqueous solution) with same colour from the following is:

$$ \mathrm{FeO}_4^{2-} \xrightarrow{+2.0 \mathrm{~V}} \mathrm{Fe}^{3+} \xrightarrow{0.8 \mathrm{~V}} \mathrm{Fe}^{2+} \xrightarrow{-0.5 \mathrm{~V}} \mathrm{Fe}^0 $$ In the above diagram, the standard electrode potentials are given in volts (over the arrow). The value of $\mathrm{E}_{\mathrm{FeO}_4^{2-} / \mathrm{Fe}^{2+}}$ is

$\mathrm{CrCl}_3 \cdot \mathrm{xNH}_3$ can exist as a complex. 0.1 molal aqueous solution of this complex shows a depression in freezing point of $0.558^{\circ} \mathrm{C}$. Assuming $100 \%$ ionisation of this complex and coordination number of Cr is 6 , the complex will be (Given $\mathrm{K}_{\mathrm{f}}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$ )

The major product of the following reaction is: $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}=\mathrm{O} \xrightarrow[\text { reflux }]{\substack{\text { excess } \mathrm{HCHO} \\ \text { alkali }}}$ ?