OnlineCBT
Chemistry · THERMODYNAMICS
हिन्दीConsider the following statements regarding the Born-Haber cycle for \( \text{NaCl(s)} \): (A) Sublimation of metallic sodium is an endothermic step. (B) Ionization of gaseous sodium atoms to \( \text{Na}^+(\text{g}) \) is an exothermic step. (C) Dissociation of \( \text{Cl}_2(\text{g}) \) molecules into \( \text{Cl}(\text{g}) \) atoms is an endothermic step. (D) Electron gain by \( \text{Cl}(\text{g}) \) to form \( \text{Cl}^-(\text{g}) \) is an exothermic step. Which of the above statements are correct?
Correct answer · Option 2
(A), (C) and (D) only
Explanation
Ionization of gaseous Na atoms requires energy (\( \Delta_i H^\ominus = +496\text{ kJ mol}^{-1} \)), so (B) is endothermic, not exothermic. (A), (C), and (D) are correct.
