Which of the following statement is not a similarity between electrostaic and gravitational forces?

Explanation

i) Gravitational forces are always attractive but electrostatic forces may be attractive or repulsive depending upon the signs of the charges.
ii) The gravitational constant (G) is independent of nature of the medium. However, electrical constant `k(=1//4pi epsilon_(0)K)` depends upon the nature of the medium.
iii) Electrostatic forces are extremely large as compared to the gravitational forces. For example, electrostatic force of attraction between an electron and a proton is about `10^(39)` times stronger than the gravitational force between them.