Hess's law states that

Options

A. The standard enthalpy of an overall reaction is the sum of the enthalpy changes in individual reactions.
B. enthalpy of formation of compound is same as the enthalpy of decomposition of the compound into constituent elements, but with opposite sign
C. at constant temperature the pressure of a gas in inversely proportional to its volume.
D. the mass of a gas dissolved per lit of a solvent is proportional to the pressure of the gas in equilibrium with the solution.

Answer

A