Identify the wrong statement in the following. Coulomb's law correctly describes the electric force that

Two electric charges $+q$ and $+q$ are placed at a distance $r$. The force between them is $F$. If one charge is fixed and the other moves in a circle of radius $r$,the work done will be .......

Two point charges placed at a distance $r$ in air experience a certain force. Then the distance at which they will experience the same force in a medium of dielectric constant $K$ is

$A$ small uncharged conducting sphere is placed in contact with an identical sphere having a charge of $4 \times 10^{-8} \text{ C}$. They are then separated to a distance such that the force of repulsion between them is $9 \times 10^{-3} \text{ N}$. The distance between them is (Take $\frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \text{ N m}^2 \text{ C}^{-2}$ in $SI$ units). (in $\text{ cm}$)

Select the correct statement from the following.

As shown in the figure,a configuration of two equal point charges $(q_0 = +2 \mu C)$ is placed on an inclined plane. The mass of each point charge is $20 \, g$. Assume that there is no friction between the charge and the plane. For the system of two point charges to be in equilibrium (at rest),the height $h = x \times 10^{-3} \, m$. The value of $x$ is $..........$. (Take $\frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \, Nm^2 C^{-2}, g = 10 \, ms^{-2}$)