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 Scroll Lock key has appeared on the keyboards of IBM personal computers since the original 83-key PC/XT and the 84-key AT layouts, and remains on the 101-key and greater enhanced keyboards currently in use. The Scroll Lock key wasn't on the original Macintosh keyboards but appears on the Mac's enhanced keyboard. The main intent of the Scroll Lock key was to allow scrolling of screen text up, down and presumably sideways using the arrow keys in the days before large displays and graphical scroll bars.