A soft keyboard (sometimes called an onscreen keyboard or software keyboard) is a system that replaces the hardware keyboard on a computing device with an on-screen image map.
An ideal gas is defined as one in which all collisions between atoms or molecules are perfectly eleastic and in which there are no intermolecular attractive forces. One can visualize it as a collection of perfectly hard spheres which collide but which otherwise do not interact with each other.
On the assumption that the ideal gas law is applicable, the humidity of a gas may be expressed in terms of its total pressure (p) and absolute temperature (T), the molecular weights of the components and the partial pressure (pv) of the vapor.