ANS:B - relative volatility

The expression 𝑦(1−𝑥)𝑥(1−𝑦)x(1−y)y(1−x)​ represents the selectivity in the context of absorption and distillation processes. In absorption and distillation, selectivity refers to the preference of one component over another in the transfer process. The expression 𝑦(1−𝑥)𝑥(1−𝑦)x(1−y)y(1−x)​ is commonly used to calculate the selectivity of one component (let's call it component A) over another (component B).

• 𝑥x represents the mole fraction of component A in the liquid phase entering the absorber or distillation column.
• 𝑦y represents the mole fraction of component A in the vapor phase leaving the absorber or distillation column.

The term (1−𝑥)(1−x) represents the mole fraction of component B in the liquid phase, while (1−𝑦)(1−y) represents the mole fraction of component B in the vapor phase. The ratio 𝑦(1−𝑥)𝑥(1−𝑦)x(1−y)y(1−x)​ quantifies how much more component A prefers to transfer to the vapor phase compared to component B. A high value of this ratio indicates a high selectivity of component A over component B, meaning that component A is preferentially transferred to the vapor phase relative to component B. Therefore, the expression 𝑦(1−𝑥)𝑥(1−𝑦)x(1−y)y(1−x)​ represents the selectivity between two components in absorption and distillation processes.