ANS:A - uses molal units for material and energy balance.

The statement "McCabe-Thiele method uses molal units for material and energy balance." is not accurate. The McCabe-Thiele method is a graphical technique used for the design and analysis of binary distillation columns. It does not inherently use molal units for material and energy balance. Instead, it typically uses molar units (moles or fractions) for expressing quantities of components in the distillation process. In the McCabe-Thiele method:

• The liquid and vapor compositions are commonly expressed as mole fractions.
• Material and energy balances are performed based on molar quantities of components.
• The method relies on graphical representations of equilibrium and operating lines to determine the number of theoretical stages required for separation.

• The McCabe-Thiele method does not use weight fractions to express liquid and vapor composition.
• The McCabe-Thiele method does not require any specific units; it can be applied with any consistent units system.
• Comparing the accuracy of the McCabe-Thiele method to the Ponchan-Savarit method depends on the specific application and assumptions made in each method. Both methods have their own advantages and limitations, and their accuracy can vary depending on the conditions of the distillation process. Therefore, it is not accurate to make a general statement that the McCabe-Thiele method is more accurate than the Ponchan-Savarit method.