ANS:C - higher steam economy.

A multiple effect evaporator, compared to a single effect evaporator of the same capacity, typically has: Higher steam economy. Here's why:

1. Lower Heat Transfer Area: Multiple effect evaporators are designed to reuse the vapor generated in one effect as the heating source for the next effect. This means that the subsequent effects require less external heat input, resulting in a lower overall heat transfer area required compared to a single effect evaporator of the same capacity.
2. Higher Steam Economy: Due to the reuse of vapor in multiple effect evaporators, they have a higher steam economy. Steam economy is a measure of the efficiency of the evaporation process and is defined as the amount of vapor produced per unit of steam used. In multiple effect evaporators, because steam is reused in subsequent effects, less fresh steam is needed overall, leading to a higher steam economy.
3. Higher Solute Concentration in the Product: Multiple effect evaporators can achieve higher solute concentrations in the product compared to single effect evaporators. This is because the multiple effect system allows for more efficient use of heat energy, enabling greater evaporation without significantly increasing the energy input.