- Afree radical
- ✓sigma complex
- Cbenzyne
- Dcarbene

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${{O}_{(g)}}+{{e}^{-}}=O_{(g)}^{-}\Delta {{H}^{o}}=-142\ kJ\,mo{{l}^{-1}}$
$O_{(g)}^{-}+{{e}^{-}}=O_{(g)}^{2-}\Delta {{H}^{o}}=844\ kJ\,mo{{l}^{-1}}$
$(I)\,\,La(OH)_3$ is the least basic among hydroxides of lanthanides.
$(II) \,\,Zr^{4+}$ and $Hf^{4+}$ posses almost the same ionic radii.
$(III)\,\,Ce^{4+}$ can as an oxidizing agent
Which of the above is/are true ?
Statement $I$ : The correct order of first ionization enthalpy values of $\mathrm{Li}, \mathrm{Na}, \mathrm{F}$ and $\mathrm{Cl}$ is $\mathrm{Na}<\mathrm{Li}<\mathrm{Cl}<\mathrm{F}$.
Statement $II$ : The correct order of negative electron gain enthalpy values of $\mathrm{Li}, \mathrm{Na}, \mathrm{F}$ and $\mathrm{Cl}$ is $\mathrm{Na}<\mathrm{Li}<\mathrm{F}<\mathrm{Cl}$
In the light of the above statements, choose the correct answer from the options given below :