It depends on what type of graph you have. The easiest would be using a H-T diagram. Enthalpy of vaporization is the physical change from liquid to vapor. It occurs at a constant pressure and a constant temperature. As shown in the picture, 1 point is drawn on the subcooled liquid, and another point of the saturated vapor isothermal line. Now, the difference between those two points is the value for the enthalpy of vaporization of water.
Explanation :
As we know that the Gibbs free energy is not only function of temperature and pressure but also amount of each substance in the system.

where,
is the amount of component 1 and 2 in the system.
Partial molar Gibbs free energy : The partial derivative of Gibbs free energy with respect to amount of component (i) of a mixture when other variable
are kept constant are known as partial molar Gibbs free energy of
component.
For a substance in a mixture, the chemical potential
is defined as the partial molar Gibbs free energy.
The expression will be:

where,
T = temperature
P = pressure
is the amount of component 'i' and 'j' in the system.
I think the correct answer would be D. The reaction that involves an acid and a covalent base would be the reaction of sulfuric acid and water or H2SO4 + 2H2O → 2H3O+ + SO42– . The acid would be H2SO4 and the covalent base would be H2O since it is being held by covalent bonds and when in solution it will have equal amounts of OH- and H+ ions.
Answer:
is equal to the total number of products
Explanation: