Calculate the percentage by mass of lead in pbco3. a.17.96 b.22.46 c.73.05 d.77.54 e.89.22

The correct answer is d.

Explanation:

Step 1: First we must obtain the molecular weight of and Pb.

= 267,21

= 207,2

Step 2: We can now calculate the percentage of lead in a molecule by stating a simple rule of three:

-->    100%.

             -->    X

%Pb =

%Pb =

%Pb = 77,54 %

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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.