MCQ Detailed View

Natural radioactivity refers to the spontaneous emission of radiation by certain elements without any external cause. It was first discovered by Henri Becquerel, a French physicist, in 1896, marking the beginning of modern nuclear physics.

🔹 Discovery Process

Becquerel was investigating phosphorescence in uranium salts, hoping that sunlight exposure would produce X-rays on photographic plates. Unexpectedly, even without sunlight, photographic plates wrapped in black paper became fogged when placed near uranium salts. This indicated that uranium was emitting some unknown form of penetrating radiation spontaneously.

🔹 Significance of the Discovery

1. 
   

   First Evidence of Radioactivity: Becquerel’s observation was the first experimental proof that atoms could emit energy on their own.

   
   


2. 
   

   Foundation for Further Research: This discovery paved the way for Marie and Pierre Curie to study radioactive elements such as polonium and radium.

   
   


3. 
   

   Development of Nuclear Physics: Becquerel’s work laid the foundation for understanding atomic structure, leading to nuclear energy and medical applications like radiotherapy.

   
   

🔹 Units and Honors

• 
  

  The unit Becquerel (Bq) is named in his honor, representing one decay per second.

  
  


• 
  

  Becquerel received the Nobel Prize in Physics in 1903, shared with the Curies, for their work on radioactivity.

  
  

🔹 Timeline

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  1766: Pre-dates discovery; unrelated

  
  


• 
  

  1896: Correct year of Becquerel’s discovery

  
  


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  1935: Not related; later developments in nuclear physics

  
  


• 
  

  2001: Modern era; not relevant to discovery

  
  

✅ Key Facts Recap

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  Discovered by: Henri Becquerel

  
  


• 
  

  Year: 1896

  
  


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  Element studied: Uranium salts

  
  


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  Importance: Launched nuclear physics and study of radioactivity

  
  


• 
  

  Unit named after him: Becquerel (Bq)

  
  

👉 Correct Answer: Option 2 – 1896