Answer-Which one of the following is a compound?

Glass Glass is a non-crystalline mixture of silica and other materials. It is not a compound because its composition is not fixed. Water Gas Water gas is a mixture of carbon monoxide CO and hydrogen H , not a compound. It is used as a fuel but doesnt have a fixed chemical formula as a single compound. CNG Compressed Natural Gas CNG is also a mixture, primarily of methane CH with small amounts of other gases. It is not a compound. Plaster of Paris POP Plaster of Paris is CaSO4 12H2O, a true chemical compound with a definite composition.