Question -Generally the ionization enthalpy in a period increases but there are some exceptions, the one which is not an exception is?
Options:
A .  Be and B
B .  N and O
C .  Mg and Al
D .  Na and Mg
Answer: Option D : D The ionization energy increases normally from sodium to magnesium as Mg has a higher effective nuclear charge as compared to Na. In the case of Be and B, and N and O, Be is more stable because of its electronic configuration.
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