Which of the following is used in the making of soft drinks ?

Carbon dioxide (CO₂) is used in the manufacture of soft drinks. It is dissolved under pressure into the beverage to create the characteristic fizz/carbonation. When the bottle is opened, the pressure is released and CO₂ escapes as bubbles. NH₃ (ammonia) is used in fertilizers, PH₃ (phosphine) is a toxic gas used as a fumigant, and COCl₂ (phosgene) is an extremely toxic gas — none of these are used in soft drinks.