The equation for the reaction of KMNO4 with FeSO4 in the acidic medium
2KMnO4 + 10FeSO4 + 8H2SO4 \(\to\) 5Fe2(SO4)3 + 2MnSO4 +K2SO4 +K2SO4 +8H2O
With the help of the equation, it is observed that 2 moles of KMnO4 will react with 10 moles of FeSO4.
Therefore, the unitary method for one mole of KnMO4 will react with 5 moles of FeSO4.
So, the correct answer (B): 5
The d-block elements are placed in groups 3-12 and F-block elements with 4f and 5f orbital filled progressively. The general electronic configuration of d block elements and f- block elements are (n-1) d 1-10 ns 1-2 and (n-2) f 1-14 (n-1) d1 ns2 respectively. They are commonly known as transition elements because they exhibit multiple oxidation states because of the d-d transition which is possible by the availability of vacant d orbitals in these elements.
They have variable Oxidation States as well as are good catalysts because they provide a large surface area for the absorption of reaction. They show variable oxidation states to form intermediate with reactants easily. They are mostly lanthanoids and show lanthanoid contraction. Since differentiating electrons enter in an anti-penultimate f subshell. Therefore, these elements are also called inner transition elements.
Read More: The d and f block elements