Concept:Thermochemical definitions are strictly based on the states of reactants and products, and the stoichiometry of the reaction.
Formula:$$ \text{Element}_{(\text{standard state})} \rightarrow 1 \text{ Mole of Gaseous Atoms} $$
Solution:- The equation shows gaseous molecular hydrogen (\( H_2 \)), which is its standard state, being converted into purely gaseous atomic hydrogen (\( H \)).
- Furthermore, exactly 1 mole of the atomic product is being formed.
- This perfectly fits the definition of standard enthalpy of atomization (\( \Delta H_{at}^\circ \)).
Why other options are incorrect:It is not formation because formation applies to compounds formed from elements. While it involves bond dissociation, 'Enthalpy of dissociation' typically refers to breaking 1 full mole of bonds (yielding 2 moles of atoms), whereas atomization specifically scales to yielding 1 mole of atoms.
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