Which of the following explains why water is a limited resource?
Water is present on Earth in a fixed amount that does not change.
Water is degrading slowly with time.
Only water not present in oceans is available for living things to use.
Once it ends up as groundwater, water is no longer available for living things to use.
Only water not present in oceans is available for living things to use.
Almost all of the water on earth is salt water in oceans.
The correct answer is: Water is present on Earth in a fixed amount that does not change.
To determine the correct option, we need to evaluate each choice based on factual information.
Choice 1: "Water is present on Earth in a fixed amount that does not change." - This statement is accurate. Water on Earth is part of a closed system, meaning the total amount of water remains fairly constant over time. While water can go through various forms, such as liquid, vapor, or ice, the total quantity does not change significantly.
Choice 2: "Water is degrading slowly with time." - This statement is not entirely accurate. Water itself does not degrade over time. However, certain water sources may become polluted or contaminated, making them unsuitable or unsafe for use. This does not mean that water as a resource is diminishing, but it highlights the importance of preserving and protecting clean water sources.
Choice 3: "Only water not present in oceans is available for living things to use." - This statement is partially accurate. Although the majority of water on Earth is present in the oceans, which are saline, it does not mean that it is unavailable for use. Through desalination processes, seawater can be converted into freshwater. However, desalination is a complex and expensive procedure, making it less accessible for widespread use.
Choice 4: "Once it ends up as groundwater, water is no longer available for living things to use." - This statement is not entirely accurate. While some groundwater can be challenging to access directly, it plays a crucial role in replenishing surface water sources, such as lakes and rivers, which are readily available for living things to use.
Therefore, out of the given choices, the correct explanation for why water is a limited resource is that water is present on Earth in a fixed amount that does not change.