Answer the following question:
 
A student is given an unknown solution X. When X is mixed with silver nitrate solution, a white precipitate is formed. The precipitate dissolves when ammonia solution is added.
 
a. Write the balanced chemical equation for the reaction.
 
b. Identify the white precipitate formed.
 
c. What is the type of reaction?
 
d. Why is the substance insoluble in water?