Calculate the number of moles containing each of the following. Express your answer to three significant figures and include the appropriate units. A.) 1.42×1022 atoms of sodium, {\rm Na} . B.)3.23×1023 molecules of dinitrogen trioxide, {\rm N}_{2}{\rm O}_{3} C.) 7.59×1024 formula units of sodium nitrite, {\rm NaNO}_{2} .