What is the AFI purity level of sodium fluoride?

The AFI purity level of sodium fluoride is indeed 0.98. This value reflects the high degree of purity typically required for sodium fluoride when used in applications such as water fluoridation and dental products. The purity level indicates that 98% of the substance consists of sodium fluoride, with minimal impurities. This level of purity is crucial because it ensures the effectiveness and safety of the compound in its various applications, particularly in public health initiatives aimed at reducing tooth decay.

The other options represent lower levels of purity, which would not meet the stringent standards required for effective use. Thus, 0.98 is recognized as the standard purity level for sodium fluoride, confirming its suitability and reliability in the aforementioned applications.