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 a comound 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 is inversely proportional to its volume
D. the mass of a gas dissolved per litre of a solvent is proportional to the pressure of the gas in equilibrium with the solution

Answer

A

Explanation

According to Hess's law the standard enthalpy of overall reaction is sum of the enthalpy change in individual reaction.