A cell has a 7.0-nm-thick membrane with a total membrane area of 6.0×10−9 m^2.a. We can model the cell as a capacitor, as we have seen. What is the magnitude of the charge on each "plate" when the membrane is at its resting potential of -70 mV? Express your answer using two significant figures.b. How many sodium ions does this charge correspond to? Express your answer using two significant figures.