I have a question can u please answer..

The question is:

Coulomb’s Force between 2 charge is independent of

1. Presence of other charge
2. Absence of other charge
3. Shape of conductor
4. All of the above

Electrostatics question based on earthing of spherical shell

an object has a charge of 2c and gains 10^19 electrons. the net chaarge on the object becomes??

A wire with a linear charge density lambda forms a quarter of a cjrclenof radius R and is placed asa shown in thefigure with its centre of curvature at the origin O the electric field at O will be

Find the value of q so that system remains in equilibrium.. figure attached below

Need to find the time taken for the dipole to come back to eqm