Final answer:
Gas, salt, and natural gas can all be mined from Earth. Natural gas is a cleaner-burning fossil fuel but poses environmental risks if not properly managed, especially when extracted via fracking. These resources are also nonrenewable and will eventually deplete.
Step-by-step explanation:
Gas, salt, and natural gas all have in common that they can be mined from Earth. Natural gas, in particular, is a fossil fuel and is considered more environmentally friendly compared to coal or oil because it emits less CO2, nitrogen oxides, and sulfur dioxide when burned. However, its extraction, especially through fracking, can cause environmental concerns such as water contamination and depletion. The fracking process involves injecting high-pressure fluids underground to fracture shale deposits and release trapped gas and oil.
Natural gas production also leads to large volumes of contaminated water that must be managed properly to prevent pollution. While natural gas, oil, and coal are derived from ancient biological material, they vary in form; coal is a solid, petroleum/oil is a liquid, and natural gas is a gaseous fossil fuel. All three forms are nonrenewable resources, which means that they cannot be replenished in a human lifetime and will eventually run out.