When an atom of n-14 is bombarded by an alpha particle, the single product is?
a. 18/9 n
b. 5/10 b
c. 18/9 f
d. 19/7 n?

For the answer to the question above asking when an atom of n-14 is bombarded by an alpha particle, the single product is?

 You're starting with 14/7 N, correct? 

An alpha particle is two protons, two neutrons, which is 4/2, correct? 
So I think the answer to your question is the third one which is c. 18/9 f 

D. most models represent a real world object in a simpler way