According to the phase diagram for water, how is the state of water determined?
1. proceed up a vertical line at any given temperature
2. read the phase at the intersection of any given temperature and pressure
3. at a given pressure, proceed horizontally to the s-l or l-g line

2. read the phase at the intersection of any given temperature and pressure

Explanation:

The phase diagram of water is a chart used to show the physical states of water at different pressures and temperatures. In a typical phase diagram, pressure is plotted against temperature. Water is known to have three states such as solid (ice), liquid (water), and gas (steam). In order to determine the physical state of water on the phase diagram, we just read the phase at the point at which the pressure and temperature values intersect. The correct answer is option (2).

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.