1. (a) River water needs to be purified to make it safe to drink. The water passes through a grid and is then left in a tank where other impurities are removed as they fall to the bottom in a process known as sedimentation. Suggest why pollutants such as fertilizers are not removed in this process.
2. (b) Drinking water can be obtained from seawater by distillation. Explain the disadvantages of using distillation to obtain large amounts of drinking water.