Kentucky Barber Practice Exam 2024 - Free Kentucky Barber Practice Questions and Study Guide.

Isopropyl alcohol is commonly used as a disinfectant because it is an effective agent against germs, bacteria, and viruses. In order for it to effectively disinfect shears or razors, the concentration of isopropyl alcohol needs to be high enough. Option D, 99%, is the best percentage for disinfecting purposes as it kills a larger percentage of germs compared to the other options. Option A (70%), B (75%), and C (90%) may still have some bacteria or germs remaining due to a lower alcohol concentration. Therefore, D, 99%, is the most effective percentage for disinfecting shears or razors.