When switch S1 is released charge on C1 is 2CV‌0 (on upper plate ) When switch S2 is released charge on C1 is CV‌0 (on upper plate) and charge on C2 is CV‌0 (on upper plate) When switch S3 is released charge on C1 is CV‌0 (on upper plate) and charge on C2 is -CV‌0 (on upper plate)