He concentration of pb2+ in a commercially available standard solution is 1.00 mg/ml. what volume of this solution should be diluted to 5.0×102 ml to produce a solution in which the concentration of pb2+ is 0.055 mg/l?

This can be directly solved using the formula:

C1 V1 = C2 V2

where C is concentration and V is volume

1.00 mg/ml * V1 = 0.055 mg/1000 ml * (5.0 x 10^2 ml)

V1 = 0.0275 ml

So 0.0275 ml is needed to be diluted to 5.0 x 10^2 ml

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.