Which quantity is same in each capacitor of series connection?

Two equal capacitors are first connected in series and then in parallel. The ratio of the equivalent capacities in the two cases will be

Consider the combination of $2$ capacitors $C_{1}$ and $C_{2}$,with $C_{2} > C_{1}$. When connected in parallel,the equivalent capacitance is $\frac{15}{4}$ times the equivalent capacitance of the same capacitors connected in series. Calculate the ratio of the capacitors,$\frac{C_{2}}{C_{1}}$.

Five capacitors each of capacity $C$ are connected as shown in the figure. If their resultant capacity is $2 \mu F$,then the capacity of each capacitor is: (in $\mu F$)

Three capacitors each of capacitance $C$ and breakdown voltage $V$ are connected in series. The capacitance and breakdown voltage of the series combination will be respectively:

Find the net capacitance between $A$ and $B$.