The standard enthalpy of formation. The enthalpy of formation is the energy change when 1 mole of a substance is formed from its constituent elements in their standard states.Particular points to note: 1  The elements are in their usual states under standard conditions. i.e at 25ÂºC and 1 atmosphere pressure (100 kPa).he standard enthalpy of formation. The enthalpy of formation is the energy change when 1 mole of a substance is formed from its constituent elements in their standard states.
Microsoft bumped the layout to 104 keys with the addition of Windows keys and a Menu key a bit later, but the layout is essentially the same. This is a rule-of-thumb, as no two keyboards are exactly the same. The number of keys on a full size keyboard varies, some having media keys, etc.
The Windows logo key is a keyboard key which was originally introduced on the Microsoft Natural keyboard in 1994. This key became a standard key on PC keyboards. Tapping this key invokes the operating system's start menu, if it has one. In Windows, Ctrl+Esc performs the same function, in case the keyboard lacks this key. Historically, the addition of two Windows keys and a menu key marked the change from the 101/102-key to 104/105-key layout for PC keyboards: compared to the former layout, a Win