Concept:Identifying the correct thermodynamic term requires matching the physical states and stoichiometry of the provided reaction equation to established definitions.
Formula:$$ \text{Element (standard state)} \rightarrow 1 \text{ mole Gaseous Atoms} $$
Solution:- The equation shows solid sodium (\( Na_{(s)} \)), which is its standard state, transforming directly into isolated gaseous sodium atoms (\( Na_{(g)} \)).
- Exactly 1 mole of gaseous atoms is produced.
- This precise transformation is the definition of the Enthalpy of atomization (\( \Delta H_{at}^\circ \)). Note: For a monoatomic solid like Na, atomization is numerically equal to the enthalpy of sublimation.
Why other options are incorrect:Enthalpy of fusion refers to Solid \( \rightarrow \) Liquid. Enthalpy of vaporization refers to Liquid \( \rightarrow \) Gas. Neither applies because this equation skips the liquid phase and starts from a solid to form gaseous atoms.
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