Eight drops of mercury, each of same radius and same charge, combine to form a bigger drop. The ratio of the capacitance of the bigger drop to that of each smaller drop is: (in $ : 1$)

The capacitance of a spherical condenser is $1\,\mu F$. If the spacing between the two spheres is $1\,mm$,then the radius of the outer sphere is

Two spherical conductors of capacities $3 \mu F$ and $2 \mu F$ are charged to the same potential,having radii $3 \ cm$ and $2 \ cm$ respectively. If $\sigma_1$ and $\sigma_2$ represent the surface charge density on the respective conductors,then $\frac{\sigma_1}{\sigma_2}$ is:

$A$ cylindrical capacitor has inner and outer conductors whose radii are in the ratio $10:1$. The inner conductor is replaced by a wire whose radius is half of the original inner conductor. To obtain the same capacitance as the original capacitor,by what ratio should the length of the wire be increased?

$A$ cylindrical capacitor has two cylinders of radii $1.4\,cm$ and $1.5\,cm$ and length $15\,cm$. The outer cylinder is earthed and the inner cylinder is given a charge of $3.5\,\mu C$. Determine the capacitance of the system and the potential of the inner cylinder.

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ Two metallic spheres are charged to the same potential. One of them is hollow and another is solid,and both have the same radii. The solid sphere will have a lower charge than the hollow one.
Reason $R:$ Capacitance of metallic spheres depends on the radii of the spheres.
In the light of the above statements,choose the correct answer from the options given below.