Q1: Water-ethyl alcohal solution can be concentrated (in respect of alcohal concentration) by __________ distillation.

ANS:B - vacuum

Water-ethyl alcohol solutions can be concentrated in terms of alcohol concentration by vacuum distillation. Vacuum distillation is commonly used to separate components with high boiling points, such as water and alcohol. By reducing the pressure in the distillation apparatus, the boiling point of the liquid mixture is lowered, allowing for the separation of components with closer boiling points than would be possible under atmospheric pressure. This enables the separation of water and alcohol, with the alcohol being distilled off at a lower temperature while leaving water behind. Therefore, vacuum distillation is the appropriate method for concentrating the alcohol in a water-ethyl alcohol solution.