The two capacitors 2μF and 6μF are put in series, the effective capacity of the system is μF is:
Three capacitors 2μF,3μF and 6μF are connected in series. The effective capacitance of the combination is:
Three capacitors each of 6μF are connected together in series and then connected in series with the parallel combination of three capacitors of 2μF,4μF and 2μF. The total combined capacity is: