Which one of the following should contain maximum DO? ans. River Ground water molten glacier and ice caps Lake

The question is asking which of the following options should contain the maximum Dissolved Oxygen (DO):

1. River
2. Ground water
3. Molten glacier and ice caps
4. Lake

Dissolved Oxygen (DO) is the amount of oxygen that is present in water. It is an important measure of water quality as it indicates a water body's ability to support aquatic life.

Here is a step-by-step analysis of each option:

1. River: Rivers often have a moderate amount of DO because they are constantly moving, which allows for more oxygen to dissolve into the water from the atmosphere. However, the amount of DO can vary depending on the temperature, salinity, and pressure of the water.

2. Ground water: Ground water typically has a low amount of DO because it is stagnant and does not have much contact with the atmosphere.

3. Molten glacier and ice caps: Glacial meltwater can have a high amount of DO because it is often cold (cold water can hold more DO than warm water) and it is exposed to the atmosphere as it melts.

4. Lake: Lakes can have varying amounts of DO depending on their conditions. For example, a eutrophic lake (one that is rich in nutrients and supports a dense plant population) may have a low amount of DO because the plants use up the oxygen for respiration. On the other hand, an oligotrophic lake (one that is nutrient-poor and has clear water) may have a high amount of DO.

Based on this analysis, the molten glacier and ice caps should contain the maximum DO because they are cold and exposed to the atmosphere. However, this can vary depending on specific conditions.