Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Ruby negi
d Option is incorrect.. option b is also correct, because if we assume sphere around origin then flux is zero and potential is constant so it create equipotential surface around origin.