The effective capacitance between points $A$ and $B$ shown in the figure is (in $\mu F$)

Three parallel plate air capacitors are connected in parallel. Each capacitor has plate area $A/3$ and separation between the plates is $d$, $2d$, and $3d$ respectively. The equivalent capacity of the combination is ($\epsilon_0$ is the permittivity of free space).

Three identical capacitors of capacitance $C$ each are connected in series and this connection is connected in parallel with one more such identical capacitor. The equivalent capacitance of the whole combination is:

Three condensers each of capacitance $2 \ F$ are connected in series. The resultant capacitance is ......... $F$.

To obtain $3\,\mu F$ capacitance from three capacitors of $2\,\mu F$ each,they will be arranged as:

The total charge on the system of capacitors with capacitances $C_{1} = 1\,\mu F$,$C_{2} = 2\,\mu F$,$C_{3} = 4\,\mu F$,and $C_{4} = 3\,\mu F$ connected in parallel is $......\,\mu C$. (Assume a battery of $20\,V$ is connected to the combination.)