What is the main constituent gas in CNG?
**Core Concept**
The main constituent gas in Compressed Natural Gas (CNG) is a key factor in its application as an alternative fuel for vehicles. CNG is a mixture of hydrocarbons, primarily composed of methane and other lighter hydrocarbons.
**Why the Correct Answer is Right**
Methane is the primary constituent of CNG, making up approximately 95% of its composition. This is due to the fact that methane is the most abundant and commercially viable hydrocarbon in natural gas. The low molecular weight and high energy density of methane make it an attractive fuel for transportation applications. The combustion of methane in CNG produces a significant amount of energy, with a higher energy density than traditional gasoline.
**Why Each Wrong Option is Incorrect**
**Option A:** Ethane is a hydrocarbon present in natural gas, but it is not the main constituent of CNG. Ethane has a higher molecular weight than methane and is less energy-dense.
**Option B:** Propane is a hydrocarbon present in natural gas, but it is not the main constituent of CNG. Propane has a higher molecular weight than methane and is less energy-dense.
**Option C:** Hydrogen is not a primary constituent of CNG. While hydrogen can be produced from natural gas, it is not a natural component of CNG.
**Clinical Pearl / High-Yield Fact**
CNG is an attractive alternative fuel due to its high energy density, low emissions, and potential for domestic production. However, the infrastructure for CNG is still developing, and its adoption is limited by the availability of CNG refueling stations.
**Correct Answer:** C. Methane.