Q1: The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is

ANS:C - -ve

In a single-component co-current absorber, the operating line represents the relationship between the mole ratio of the solute in the liquid phase (typically the solvent) to the solute in the gas phase (typically the absorbate) at various stages of the absorption process. Since the mole ratio represents the ratio of the number of moles of the solute in the liquid phase to the number of moles of the solute in the gas phase, it reflects the concentration gradient along the absorber. The slope of the operating line in terms of mole ratio units will be positive, indicating that as the mole ratio increases (i.e., more solute is present in the liquid phase relative to the gas phase), the operating line moves upward along the graph. So, the correct answer is: +ve (positive).