MCQ Detailed View

Alpha particles are a type of ionizing radiation emitted during the radioactive decay of certain heavy elements, such as uranium, radium, and polonium. They are considered one of the three primary forms of nuclear radiation, along with beta particles and gamma rays.

Structurally, an alpha particle is a compact cluster of two protons and two neutrons, identical to the nucleus of a helium-4 atom. This gives it a +2 positive charge because it contains protons but no surrounding electrons. Its mass is relatively large compared to other forms of radiation.

Key characteristics of alpha particles:

1. 
   

   Composition: 2 protons + 2 neutrons (same as helium nucleus).

   
   


2. 
   

   Charge and Mass: Positively charged with a mass four times that of a hydrogen atom.

   
   


3. 
   

   Speed: Travels at high speeds but slower than beta particles due to greater mass.

   
   


4. 
   

   Penetrating Power: Low; alpha particles can be stopped by a sheet of paper or even the outer layer of human skin.

   
   


5. 
   

   Ionizing Ability: Very high; they can cause significant damage to living cells if radioactive sources emitting alpha particles are inhaled or ingested.

   
   

Other options are incorrect:

• 
  

  Electron and Proton: This combination forms a hydrogen atom, not an alpha particle.

  
  


• 
  

  Three protons and three neutrons: Such a particle does not naturally exist in nuclear radiation.

  
  

Alpha particles play an important role in nuclear reactions, radiation therapy, and research in atomic physics. Their predictable behavior helps scientists understand radioactive decay series and nuclear stability.

Thus, the correct answer is Two Protons and Two Neutrons, as this is the true composition of an alpha particle emitted during nuclear decay.