ANS:D - 98

The conversion of ammonia (NH3) to nitrogen oxide (NO) during the catalytic oxidation process in the manufacture of nitric acid typically achieves a high level of efficiency. The conversion rate is approximately 98 percent. The high conversion rate of around 98 percent from ammonia (NH3) to nitrogen oxide (NO) during the catalytic oxidation process in the manufacture of nitric acid is achieved due to several factors:

1. Catalyst: The reaction is facilitated by a catalyst, typically platinum or a platinum-rhodium alloy, which enhances the conversion efficiency by providing an active surface for the reaction to occur.
2. Temperature: The reaction is carried out at a relatively high temperature of around 800°C. At this temperature, the ammonia molecules possess sufficient kinetic energy to overcome the activation energy barrier for the reaction, leading to a higher conversion rate.
3. Residence Time: The reaction mixture is allowed sufficient time to react in the presence of the catalyst. This ensures that most of the ammonia molecules come into contact with the catalyst surface, leading to a higher conversion efficiency.
4. Catalyst Activity: Platinum-based catalysts are highly active and selective for the oxidation of ammonia to nitrogen oxide. They promote the desired reaction while minimizing side reactions, resulting in a high conversion rate.