Which of the field patterns given below is valid for electric field as well as for magnetic field?

$A$ circular ring carries a uniformly distributed positive charge. The electric field $(E)$ and potential $(V)$ vary with distance $(r)$ from the centre of the ring along its axis as:

Three identical charges are placed at the three corners of an equilateral triangle as shown in the figure. Which of the following statements is true for the electric field $E$ and electric potential $V$ at the center $O$?

Two identical charges $Q$ are separated by a distance $r$. $A$ third charge $q$ is placed at the midpoint of the line joining the two charges such that all three charges are in equilibrium. In this state,$q = $ . . . . . . .

Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of $30^o$ with each other. When suspended in a liquid of density $1 \, g \, cm^{-3}$,the angle remains the same. If the density of the material of the sphere is $4/3 \, g \, cm^{-3}$,the dielectric constant of the liquid is:

Three point charges are placed at the corners of an equilateral triangle of side $L$ as shown in the figure.