The correct option for the given reaction is **D. endothermic**. ### Explanation of the Correct Answer 1. **Understanding the Reaction**: The reaction provided is: \[ 3C(s) + 2Fe_2O_3(s) \rightarrow 4Fe(s) + 3CO_2(g) \] The enthalpy change (\(\Delta H\)) for this reaction is given as +46.0 kJ. 2. **What Does \(\Delta H\) Mean?**: The enthalpy change (\(\Delta H\)) indicates whether a reaction absorbs or releases heat. - A positive \(\Delta H\) value means that the reaction absorbs heat from the surroundings. This is characteristic of an **endothermic reaction**. - Conversely, a negative \(\Delta H\) would indicate an **exothermic reaction**, where heat is released. 3. **Conclusion**: Since the \(\Delta H\) for this reaction is +46.0 kJ, it confirms that the reaction is endothermic. The system absorbs 46.0 kJ of energy to proceed with the reaction. ### Explanation of Why Other Options Are Incorrect - **A. Isothermic**: - An isothermic process occurs at a constant temperature. While it is possible for a reaction to be isothermic, the key factor here is the enthalpy change. The positive \(\Delta H\) indicates that heat is absorbed, which does not necessarily imply constant temperature. Therefore, this option is not applicable. - **B. Adiabatic**: - An adiabatic process is one in which no heat is exchanged with the surroundings. Since the reaction absorbs heat (as indicated by the positive \(\Delta H\)), it cannot be adiabatic. Thus, this option is also incorrect. - **C. Isobaric**: - An isobaric process occurs at constant pressure. While many reactions can occur at constant pressure, the defining characteristic of this reaction is its enthalpy change. The positive \(\Delta H\) indicates that it is endothermic, not necessarily that it occurs at constant pressure. Therefore, this option does not directly address the nature of the heat exchange in the reaction. ### Summary of Key Concepts - **Endothermic Reaction**: A reaction that absorbs heat from the surroundings, indicated by a positive \(\Delta H\). - **Enthalpy Change (\(\Delta H\))**: A measure of the heat content of a system; positive values indicate heat absorption. - **Isothermic, Adiabatic, and Isobaric**: Terms that describe specific conditions of temperature, heat exchange, and pressure, respectively, but do not directly relate to the heat absorption characteristic of this reaction. ### Revision Summary - The reaction is **endothermic** because it has a positive \(\Delta H\) (+46.0 kJ). - Endothermic reactions absorb heat from their surroundings. - Isothermic, adiabatic, and isobaric describe conditions that do not directly relate to the heat absorption characteristic of this reaction. - Always check the sign of \(\Delta H\) to determine if a reaction is endothermic or exothermic.