Question

why first ionization enthanpy is lower than that of zinc
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Answer 1

Answer:

onisation enthalpy of Cr is less than that of Zn because Cr has stable configuration. In case of zinc, electron comes out from completely filled 4s - orbital. So, removal of electron from zinc requires more energy as compared to the chromium.

Answer 2

Answer:

➠Ionisation enthalpy of Cr is less than that of Zn because Cr has-

$3 {d}^{5} 4 {s}^{1} configuration$

➠In case of zinc, electron comes out from completely filled -

${4s}^{2} orbital \: which \: is \: stable \: than \: {4s}^{1} in \: cr$

➠So, removal of electron from zinc requires more energy as compared to the chromium.