In order to ensure that comparisons of changes in enthalpy for reactions can be made, measurements of changes in enthalpy must be made under the conditions of a. 298 K, 1 atm pressure, 1 M concentration for ions, and specified physical states. b. 0°C, 1 atm pressure, 1M concentration, and specified physical states. c. 273 K, 1 atm pressure, and 1M concentration. d. 298 K, 1 atm pressure, and 1 M concentration. e. 273 K, 1 atm pressure, 1M concentration, and specified physical states. Solution Thermodynamics property are measured at standard condition. It should not be confused with STP The temperature for measurement is 298 K Pressure is 1 atm ions concentration should be 1 M and physical state should be specified Answer: a .