question_answer 70)

  In which of the following options, order of arrangement does not agree the variation of property indicated against it? (a) \[A{{l}^{3+}}<M{{g}^{2+}}<N{{a}^{+}}<{{F}^{-}}\] (increasing ionic size) (b) \[B\text{ }<\text{ }C\text{ }<\text{ }N\text{ }<\text{ O}\] (increasing first ionisation enthalpy) (c) \[I\text{ }<\text{ }Br\text{ }<\text{ }Cl\text{ }<\text{ }F\] (increasing electron gain enthalpy) (d) \[I\text{ }<\text{ }Br\text{ }<\text{ }Cl\text{ }<\text{ }F\] (increasing metallic radius)

Answer:

  (b, c) For increasing first ionisation enthalpy, the order should be: \[B\text{ }<\text{ }C\text{ }<\text{ }O\text{ }<\text{ }N.\]                 For increasing electron gain enthalpy, the order should be: \[I\text{ }<\text{ }Br\text{ }<\text{ }F\text{ }<\text{ }Cl.\]