Answer:
The formula for the precipitate is PbI₂
Explanation:
The chemical reaction is:
Pb(NO₃)₂ (aq)  +  2KI (aq)  →  2KNO₃ (aq) + PbI₂ (s)↓
All the iodides, with these cations (Ag⁺, Pb²⁺, Cu⁺, Hg²⁺, Bi⁺³ and Sn⁺⁴) produce insolubles solid. 
 
        
             
        
        
        
Answer:
Five
Explanation:
Valance electrons are the outermost electrons in an atom. There are five electrons in the third layer of the phosphorus atom. So your answer is five valance electrons.
 
        
             
        
        
        
Chemical bonds are formed or broken. This is true of a chemical change, but not a physical change. A physical change is usually something that you can see, such as changing of shape or form or staying the same.  However, because you cannot visibly see chemical bonds being formed or broken and because this would affect the chemical composition, it is not a physical change.