If the velocity of light , acceleration due to gravity and the normal pressure are choosen as the fundamental units, find the units of mass, length and time . Given that velocity of light c=3×10^8ms^-1, acceleration due to gravity , g=10ms^-2 and normal atmospheric pressure p=10^5N/m²​

It really doesn't matter for any of the questions that you've listed.

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.