Work done in moving a positive charge on an equipotential surface is

A block of mass $m$ containing a net negative charge $-q$ is placed on a frictionless  horizontal table and is connected to a wall through an unstretched spring of spring  constant $k$ as shown. If horizontal electric field $E$ parallel to the spring is switched on,  then the maximum compression of the spring is :-

Define electron Volt and convert it into Joule unit.

The work which is required to be done to make an arrangement of four particles each having a charge $+q$ such that the particles lie at the four corners of a square of side $a$ is .......

Which of the following statement$(s)$ is/are correct?

$(A)$ If the electric field due to a point charge varies as $r^{-25}$ instead of $r^{-2}$, then the Gauss law will still be valid.

$(B)$ The Gauss law can be used to calculate the field distribution around an electric dipole.

$(C)$ If the electric field between two point charges is zero somewhere, then the sign of the two charges is the same.

$(D)$ The work done by the external force in moving a unit positive charge from point $A$ at potential $V_A$ to point $B$ at potential $V_B$ is $\left(V_B-V_A\right)$.

The work done to take an electron from rest where potential is $-60\, V$ to another point where potential is $-20\, V$ is given by.....$eV$