If Sodium Chloride is added to Silver Nitrate,A) it first turns to a cloudy white colour and B) after being left in the dark (white solid/clear liquid) and light (brown solid/clear liquid) it turns to its respective solids with clear liquid. What are A) and B) reactions (Double Displacement Formation, precipitation or decomposition, synthesis or single displacement)?
You have two reactions occurring here. The first is the addition of NaCl to AgNO3. This produces AgCl and NaNO3 according to the reaction below:
NaCl + AgNO3 --> AgCl (s) + NaNO3
This is a double displacement reaction since both sets of ions switch places with each other. AgCl is not soluble in water and precipitates out as a solid to make the mixture look cloudy white like milk. If kept in the dark, the mixture will stay this way. But on exposure to light, the second reaction happens. This is the decomposition of the AgCl into silver metal and chlorine gas:
2AgCl --> 2Ag + Cl2
The silver solid is the dark colored solid and the chlorine will simply bubble out of solution. As stated earlier, this is a decomposition reaction.