1. A countercurrent leaching system is to treat 100 kg/h of crushed sugar stalks with impurity-free water as the solvent. Analysis of the stalks is as follows: Water: 38% (by mass), Sugar: 10%, Pulp: 52%. If 95% sugar is to be recovered and the extract phase leaving the system is to contain 12% sugar, determine the number of theoretical stages required if each kilogram of dry pulp retains 2.5 kg of solution. Assume an over-all stage efficiency of 95%