Minerals And Rocks

Petroleum is often referred to as "liquid gold" because of its immense value and importance in the global economy. Just as gold has been historically valuable for trade and wealth, petroleum has become equally crucial in modern society due to its wide range of applications and its role as a key energy source.
- Energy Source: Petroleum is a primary source of energy for transportation, electricity generation, and heating. It is a critical raw material for producing fuels such as gasoline, diesel, and jet fuel.
- Industrial Applications: Petroleum and its by-products are essential in the production of chemicals, plastics, synthetic materials, and fertilizers.
- Economic Impact: Like gold, petroleum is an economic driver. Countries with large petroleum reserves, such as Saudi Arabia and Russia, have significant influence over global energy markets.
The term "liquid gold" emphasizes the economic and strategic importance of petroleum, comparable to the way gold has historically been a symbol of wealth and power.

Underground mining is used when the ore lies deep below the surface (i). This method involves specialized equipment such as lifts and drills (iii). It is also known as the shaft method (iv), where a shaft is dug vertically to reach the ore. However, it is not the easiest or cheapest method (ii), as it is more costly and complex compared to surface mining.

Surface mining is primarily used for extracting minerals that are near the earth's surface. It is the most cost-effective and safest method compared to underground mining. However, statement iii is incorrect because surface mining is not used for extracting minerals from deeper parts of the earth. Instead, deeper mining methods are employed for that purpose. Additionally, surface mining is often referred to as open cast mining, which is reflected in statement iv.