Mole ratio :
5 C₆H₆CHO + 2 KMnO₄ + 6 H⁺ = 5 C₆H₆COOH + 2 Mn²⁺ + 3 H₂O + 2 K⁺
5 moles C₆H₆CHO ------------------ 2 moles KMnO₄
1.0 moles C₆H₆CHO ---------------- ( moles of KMnO₄ )
moles of KMnO₄ = 1.0 x 2 / 5
moles of KMnO₄ = 2 / 5
= 0.40 moles of KMnO4
hope this helps!