Meq of oxidizing agent = Meq of reducing agent (M×V×nF)KMnO4=(M×V×nF)Mohr′‌ salt ‌ 0.01×20×5=0.05×V×1 Volume required =20‌ml Since initial volume of KMnO4 in burette is 50‌ml. Hence volume of KMnO4 left in the burette after end point is 30‌ml.