7:
1. Galvani's Animal Electricity: These coins highlight Luigi Galvani's experiments on animal electricity, leading to the concept of bioelectricity.
2. Salk's Polio Vaccine: Commemorate Jonas Salk's development of the polio vaccine, a monumental achievement in the field of public health.
3. Rontgen's Discovery of Cathode Rays: Unveil the mystery of cathode rays with these coins honoring Wilhelm Conrad Roentgen's significant discovery.