ANS:A - 2

The diameter of Raschig rings used in packed towers in industry is typically around 2 inches. Raschig rings are a type of random packing material commonly used in packed columns for gas-liquid contact operations such as absorption, distillation, and stripping. They consist of cylindrical rings with a diameter roughly equal to their height. The size of the Raschig rings can vary depending on the specific application and design requirements of the packed column. However, in industrial applications, Raschig rings with a diameter of approximately 2 inches (50.8 mm) are commonly used. This size provides a good balance between surface area for mass transfer and pressure drop in the packed column.