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

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

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

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. Ground water: Ground water is usually low in DO because it is isolated from the atmosphere and contains decaying organic matter that consumes oxygen.

2. River: Rivers usually have moderate levels of DO. The level of DO in a river depends on the temperature, salinity, and pressure of the water. Fast-moving rivers tend to have higher DO levels because they are constantly being aerated.

3. Lake: Lakes usually have moderate to high levels of DO. The level of DO in a lake depends on the temperature, salinity, and pressure of the water. Lakes that are exposed to wind and waves tend to have higher DO levels because they are constantly being aerated.

4. Molten glacier and ice caps: Glacial meltwater and ice caps have the highest levels of DO. This is because cold water can hold more dissolved oxygen than warm water. Also, glacial meltwater and ice caps are isolated from pollution and human activity, which can decrease DO levels.

Therefore, the answer is molten glacier and ice caps.