ANS:B - marginal decrease in the number of

Lowering the distillate quality from 95% to 92% in an ethanol-water system would actually cause a marginal increase in the number of theoretical plates required, not a decrease. Here's the explanation: Distillate quality refers to the purity of the distillate obtained from a distillation process. When the distillate quality decreases, it means that more impurities are present in the distillate. To achieve a lower distillate quality, more separation is needed, which requires more theoretical plates in the distillation column. Therefore, when the distillate quality decreases from 95% to 92%, a marginal increase in the number of theoretical plates is required to achieve the desired separation and maintain the distillate quality within the specified range.