The equivalent capacitance between $A$ and $B$ is.......$\mu \,F$

The equivalent capacitance between $A$ and $B$ is......$\mu F$.

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).

Four capacitors of equal capacity have an equivalent capacitance $C_{1}$ when connected in series and an equivalent capacitance $C_{2}$ when connected in parallel. The ratio $\frac{C_{2}}{C_{1}}$ is:

Four capacitors with capacitances $C_1 = 1 \, \mu F$,$C_2 = 1.5 \, \mu F$,$C_3 = 2.5 \, \mu F$,and $C_4 = 0.5 \, \mu F$ are connected as shown and are connected to a $30 \, V$ source. The potential difference between points $B$ and $A$ is....$V$

The combination of capacitors with $C_1 = 3\,\mu F$,$C_2 = 4\,\mu F$,and $C_3 = 2\,\mu F$ is charged by connecting $A$ and $B$ to a battery. Consider the following statements:
$I.$ Energy stored in $C_1$ $=$ Energy stored in $C_2$ $+$ Energy stored in $C_3$
$II.$ Charge on $C_1$ $=$ Charge on $C_2$ $+$ Charge on $C_3$
$III.$ Potential drop across $C_1$ $=$ Potential drop across $C_2$ $=$ Potential drop across $C_3$
Which of these is/are correct?