Capacitance question bank (Physics)

Three parallel plate capacitors $\mathrm{C}_1, \mathrm{C}_2$ and $\mathrm{C}_3$ each of capacitance $5 \mu \mathrm{~F}$ are connected as shown in figure. The effective capacitance between points A and B, when the space between the parallel plates of $C_1$ capacitor is filled with a dielectric medium having dielectric constant of 4, is :

Four capacitor each of capacitance $16 \mu \mathrm{~F}$ are connected as shown in the figure. The capacitance between points A and B is : ______ (in $\mu \mathrm{F}$).