Q1: The actual temperature drop across the heating surface of an evaporator depends on the

ANS:D - all (a), (b) and (c)

The actual temperature drop across the heating surface of an evaporator depends on several factors, including: a) Liquid depth over the heating surface: The temperature drop across the heating surface can be influenced by the depth of the liquid over the heating surface. A greater liquid depth may lead to a smaller temperature drop, as there is more liquid available to absorb the heat generated by the heating surface. b) Solution being evaporated: The properties of the solution being evaporated, such as its composition, viscosity, and heat capacity, can affect the temperature drop across the heating surface. Different solutions may require varying amounts of energy to undergo evaporation, leading to differences in the temperature drop. c) Pressure difference between the steam chest and the vapor space above the boiling liquid: The pressure difference affects the boiling point of the liquid in the evaporator. A higher pressure difference typically results in a higher boiling point, which in turn affects the temperature drop across the heating surface. Therefore, the correct answer is: d) all (a), (b), and (c). The actual temperature drop across the heating surface of an evaporator depends on the liquid depth over the heating surface, the solution being evaporated, and the pressure difference between the steam chest and the vapor space above the boiling liquid.