Final answer:
Pipelines are primarily used for transporting liquids and gases. Airfreight is the most expensive but fastest mode of cargo transportation. High-value, low-weighted goods are typically shipped by airfreight.
Step-by-step explanation:
The primary use of pipelines is transporting liquids and gases, which can include commodities such as oil, natural gas, and chemicals. While pipelines are not often used for high-value goods, low-weighted goods, or large quantities of perishable goods, they are integral for the movement of various liquid and gas products due to their efficiency in continuously moving these commodities over long distances.
The mode of cargo transportation that is described as the most expensive but fast is airfreight. Airfreight is typically used for goods that must be delivered quickly over long distances. Its speed compared to other modes of transportation like maritime shipping, rail transport, or trucking justifies the additional cost.
Typically, goods that are high-value and low-weighted are shipped by airfreight, according to the information provided. These can include items such as electronics, pharmaceuticals, and other high-value commodities where the cost of fast delivery is offset by the value of the goods themselves.