#famous_discoveries: ✅ Radioactivity was discovered by Henri Becquerel in 1896 ✅ X-Ray was discovered by Roentgen 1895 ✅ Oxygen was discovered by Joseph Priestley in 1774 ✅ Soda water was discovered by Joseph Priestley in 1767 ✅ Gama Rays were discovered by Paul Villard in 1900.