Calculate the Average Atomic Mass of the Lead-204, Lead-206, Lead-207, and Lead- 208. [Include the unit! amu]

Density= mass/volume so 5.1 divided by 4.7 is  5.1 / 4.7 =1.08510638298round to the correct number of sig figs

In reversible reaction chemistry equilibrium is attained when the forward and reverse reactions are taking place at the same rate, thus, the concentrations of reactants and products remain the same. a reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. in irreversible reactions on the other hand, the reactants react to form the products, which cannot revert back into reactants.

Moles = mass/molar mass the molar mass of c20 = 12.011*20 = 240.22 g per mole therefore, the number of moles is 20 g / 240.22 g per mol = 0.0833 moles.

The correct answer is:   [a]:   the "stratosphere" .