Briefly explain London or disperison forces

Explanation

These are intermolecular force. Which exists in monoatomic gases like He,Ne etc and homodiatomic molecules (non-polar molecules) 1/He, `H_(2), O_(2), N_(2)` etc. This was first explained by Fritz london in 1930. According to him, in non-poar and monoatomic gases, there is symmetrical distributaion of electron cloud. Due to the movement of electrons cloud gets destarded so that a momentary dipole is produces. In this one will be more negative. therefore, two molecules attract each other and his in London force.