The crossword solution for the term GREEN GAS is CHLORINE, an 8-letter word. CHLORINE is a chemical element with the symbol Cl and atomic number 17. It is a halogen, found in the periodic table in group 17. CHLORINE is a greenish-yellow gas at room temperature and pressure. It is one of the most common elements in the Earth's crust and is essential to life. CHLORINE is used in many industrial processes, such as water treatment, bleaching, and disinfection.