What is the equivalent capacitance between the points $P$ and $Q$ in the combination of capacitors shown in the figure (in $\mu F$)?

The equivalent capacitance between points $A$ and $B$ as shown in the figure is:

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:

Two condensers of capacities $1\,\mu F$ and $2\,\mu F$ are connected in series and the system is charged to $120\,V$. Then the potential difference $(P.D.)$ across the $1\,\mu F$ capacitor (in $volts$) will be

An infinite number of identical capacitors,each of capacitance $1\,\mu F$,are connected as shown in the adjoining figure. The equivalent capacitance between $A$ and $B$ is......$\mu F$.

Three capacitors $1\,\mu F$,$2\,\mu F$,and $4\,\mu F$ are connected in series to a $10\,V$ source. The charge on the plates of the middle capacitor is: