Four metal conductors having different shapes such that of1. a sphere3. a pear2. a cylinder4. a lightning conductorare mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is

In case of spherical metal conductor, the charges quickly spread uniformly over the entire surface because of which charges stay for longer time on the spherical surface. While in case of non-spherical surface, the charge concentration is different at different points due to which the charges do not stay on the surface for longer time.