The answer to your question is letter D. Secured.
 
        
             
        
        
        
Answer:
Nuclear reaction takes place at the nucleus whereas chemical reaction involves valence electrons
Explanation:
 
        
             
        
        
        
"Pent" is five, "ene" means double bonded carbon
        
             
        
        
        
Answer:
The answer to your question is: The mass number will be 4 units lower.
Explanation:
Alpha particles are Helium atoms, which have a mass number of 4 and atomic number of 2.
When an alpha particle is released, the original atom loses 2 protons and and 2 neutrons an we can see in the example.
                              ²²⁶ ₈₈ Ra  ⇒   ²²² ₈₆ Rn   +   ⁴₂ He