Which of the following is considered an inexhaustible natural resource, meaning it is not likely to be depleted by normal human use?

Introduction / Context:

This question belongs to environmental physics and earth science. Natural resources are often classified as exhaustible (non renewable) or inexhaustible (practically unlimited). Understanding which resources can run out and which are continuously available helps guide sustainable development, conservation efforts, and energy planning.

Given Data / Assumptions:

• The options list air, minerals, forests, and coal as natural resources.
• Inexhaustible resources are those that are continuously available and are not significantly depleted by normal human use over practical timescales.
• Exhaustible resources are limited in quantity and can be depleted by excessive use.
• We assume typical school level classifications of resources.

Concept / Approach:

Air is generally classified as an inexhaustible natural resource because the atmosphere is vast and continuously renewed by natural processes such as photosynthesis, respiration, and circulation. Although air quality can be degraded, the total supply is not easily depleted. In contrast, minerals, forests, and coal are considered exhaustible. Minerals and coal take geological timescales to form and can be used up. Forests, while renewable with careful management, can be depleted faster than they regrow and so are often treated as exhaustible resources in practice. Therefore, air is the correct answer.

Step-by-Step Solution:

Verification / Alternative check:

Environmental science textbooks commonly list air and solar energy as classic examples of inexhaustible or practically inexhaustible resources. They list coal, petroleum, natural gas, and mineral ores as exhaustible natural resources. Forests are often placed in a separate category of renewable but exhaustible if overused. This classification aligns with the reasoning above and leaves air as the correct choice.

Why Other Options Are Wrong:

• Minerals: Available in limited quantities in ore bodies; excessive mining can deplete economically viable deposits.
• Forests: Can be destroyed by deforestation faster than natural regrowth, leading to serious loss of forest cover.
• Coal: A fossil fuel that takes millions of years to form and is being used far more rapidly than it forms, making it exhaustible.

Common Pitfalls:

Students may confuse renewable with inexhaustible. A resource can be renewable but still exhaustible if misused, such as forests and freshwater in local regions. Inexhaustible refers to resources that are effectively unlimited on human timescales, such as air moving in the atmosphere and solar energy from the Sun. Recognising this distinction helps in correctly categorising different types of natural resources.

Final Answer:

Air is considered an inexhaustible natural resource.