Answer :
To find the charge on each capacitor in series, first calculate the equivalent capacitance and then the charge using the potential difference. The charge is equal on both, but the voltage is distributed inversely to their capacitances.
When a 4.00-pF capacitor is connected in series with an 8.00-pF capacitor and a 400-V potential difference is applied across the pair, the charge Q on each capacitor is the same because they are in series. To find the charge, we first calculate the equivalent capacitance Ceq of the series combination using the formula:
1/Ceq = (1/C1) + (1/C2)
Where C1 = 4.00 pF and C2 = 8.00 pF.
Then we use the relationship Q = Ceq * V to find the charge, where V is the potential difference across the series combination. Since the capacitors are in series, the voltage across them is not the same and it is distributed inversely proportional to the capacitance. To find the voltage across each capacitor, use V = Q / C for each one separately.