Explanation

• Radioactivity was discovered by Henri Becquerel, a French physicist, in 1896.
• He discovered this when he was studying uranium and noticed that it emitted radiation without an external source of energy.
  
• The term radioactivity was coined by Marie Curie, who, along with her husband, investigated this phenomenon.
• Rutherford, a British physicist, studied the properties of radioactive decay and named the particles alpha, beta and gamma.