what is the most common propellant for a rocket

The most common propellants for rockets are liquid and solid propellants. Liquid chemical rockets typically use two separate propellants: a fuel and an oxidizer. Typical fuels include kerosene, alcohol, hydrazine, and liquid hydrogen, while oxidizers include nitric acid, nitrogen tetroxide, liquid oxygen, and liquid fluorine. Some of the most common liquid rocket propellants are liquid hydrogen and liquid oxygen, which offer high specific impulse and are used in upper stages of rockets that operate in the vacuum of space. Additionally, rocket-grade kerosene (RP-1) is commonly used as a fuel with liquid oxygen. Solid propellants come in two main types: "composites" and "double-base propellants". Composites are composed mostly of a mixture of solid oxidizer, such as ammonium nitrate, in a polymer binding agent, with flakes or powders of energetic fuel compounds. The most common monopropellant is hydrazine, which is used for attitude control and spacecraft station-keeping. Hypergolic propellants, such as hydrazine and dinitrogen tetroxide, are also commonly used in rocket engines. Therefore, the most common propellants for rockets are a combination of liquid and solid propellants, including liquid hydrogen, liquid oxygen, rocket-grade kerosene, and hydrazine.