How many moles of carbon are in 7.87x10^7 carbon atoms?

There are about 6.022*10^23 molecules in 1 mole of carbon

Lets say that the required number of moles will be x

1 mole —6.022*10^23

x moles—7.87*10^7

Cross multiply

x=7.87*10^7/6.022*10^23

Answer x=1.3*10^-16

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.

a