Do S and Na have the same number of
electron shelis?

Yes

Explanation:

Sulfur and Sodium will have the same number of electron shells.

  Electronic configuration of

           k   l  m

  Na = 2  8  1

   S =  2  8  6

We see that the have the same energy level.

Also, they belong to the same period on the periodic table. Elements in the same period will have equal number of shell.

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.