ANS:A - in liquid phase

Urea is typically formed in the liquid phase through a chemical reaction known as the urea synthesis reaction. This reaction occurs between ammonia (NH3) and carbon dioxide (CO2) in the presence of a suitable catalyst under elevated pressure and temperature conditions. The process, known as the Bosch-Meiser urea process, usually operates at temperatures ranging from 150°C to 210°C and pressures between 150 to 200 atmospheres. These conditions favor the formation of urea. So, the correct option is: in liquid phase