In the given chemical reaction, colors of the Fe²⁺ and Fe³⁺ ions, are respectively :
5Fe²⁺ + MnO₄ - + 8H⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺

Solution

Chemistry ma’am · 3 steps

Iron(II) solutions look pale green and iron(III) solutions look yellow, so read the ions before and after.

1. What changes. MnO₄⁻ in acid oxidises Fe²⁺ to Fe³⁺, and is itself reduced to Mn²⁺. Iron loses one electron, going from 3d⁶ to 3d⁵.

   Ion	Configuration	Colour in water
   Fe²⁺	3d⁶	pale green
   Fe³⁺	3d⁵	yellow (yellowish brown)
   MnO₄⁻	Mn in +7 state	deep purple
   Mn²⁺	3d⁵	almost colourless (very pale pink)

2. Colour of the ions. Hydrated Fe²⁺ is pale green, as in a solution of FeSO₄. Hydrated Fe³⁺ is yellow, as in a solution of FeCl₃.
3. So. In order, the colours are green for Fe²⁺ and yellow for Fe³⁺, which is option (d).

The idea to keep. Remember the iron pair: Fe²⁺ is green and Fe³⁺ is yellow. When the green turns yellow, iron has been oxidised.

Answer from the NTA final answer key. Solution by PrepWiser.