Answer : To balance a chemical equation you need to find the same number of molecules on both the sides of the reaction.
Here in the reaction ;
[tex]KI + Pb (NO_{3})_{2}----\ \textgreater \ Pb I_{2} + KNO_{3} [/tex]
here we can see that I is not balanced so we need to balance that,
also nitrate is unbalanced we need to work on that as well.
so on solving we get,
[tex]2KI + Pb (NO_{3})_{2}----\ \textgreater \ Pb I_{2} + 2KNO_{3} [/tex]
