How many moles of carbon are in 7.87*10^7 carbon atoms

1.31*10^-16moles

Explanation:

If 1 mole of carbon contains 6.02*10^23 carbon atoms (Avogadro's number)

X moles of carbon contain 7.87*10^7 carbon atoms

X = 7.87*10^7/6.02*10^23

X = 1.31*10^-16moles

Note that 1 moles of any substance contains Avogadro's number of elementary entities (atoms, ions, molecules etc)

There is 7 moles in C