[" 38.An isolated and charged spherical soap bubble has a radius "r" and "],[" the pressure inside is atmospheric.If "T" is the surface tension of "],[" soap solution,then charge on drop is "],[[" (a) "2sqrt((2rT)/(varepsilon_(0)))," (b) "8 pi r sqrt(2rT varepsilon_(0))],[" (c) "8 pi r sqrt(rT varepsilon_(0))," (d) "8 pi r sqrt((2rT)/(varepsilon_(0)))]]