1. In the notation of the symbol XZA, if Z \(=\)  12 and A \(=\) 24, (i) find the number of neutrons in the atom and (ii) identify the element X.
  
Answer:
 
(i) 
 
(ii) The element is .
 
2. Calculate the mass number of an element with atomic number 12 and has 17 neutrons.
 
Answer: