GENERAL KNOWLEDGE

Detailed explanation-1: -Cryogenic engines find applications in rocket technology. A cryogenic rocket engine is a rocket engine that uses a cryogenic fuel and oxidizer; that is, both its fuel and oxidizer are gases that have been liquefied and are stored at very low temperatures.

Detailed explanation-2: -The United States, Russia, Japan, India, France and China are the only countries that have operational cryogenic rocket engines.

Detailed explanation-3: -The most common cryogenic propellants used in rocket engines are liquid hydrogen (LH2), which liquefies at −253° C, as the fuel and liquid oxygen (LOX), which liquefies at −183° C, as the oxidiser.