Find the mass of the system:
(508) * (1.673x10^-27 kg) + (952) * (9.11x10^-31 kg) = 8.51x10^-25 kg
(The electrons barely make a difference at all)
For the first question I'm pretty sure you're assuming that each carbon atom has 6 electrons; you can figure it out from there.
The second question seems a bit on the tougher side too so I'll do that one.
1 millionth of all the oxygen molecules has a positive charge (lost one electron), so find the total number of molecules, divide by a million, and multiply by the charge of a proton.
(1.20) * (6.02x10^23) * (1/1,000,000) * (1.6x10^-19) = .116 C
Hope this helped :)