In which of the following options order of arrangement does not agree with the variation of property indicated against it ? A) `Al^(3+) lt Mg^(2+) lt Na^(+) lt F^(-)` (increasing ionic size) B)`B lt C lt N lt O` (increasing first ionisation enthalpy) C)`I lt Br lt Cl lt F` (increasing electron gain enthalpy) D)`Li lt Na lt K lt Rb` (increasing metallic radius)

Options

A. `B lt C lt N lt O` (increasing first ionisation enthalpy)
B. `I lt Br lt CI lt F` (increasing electron gain enthalpy)
C. `Li lt Na lt k lt Rb`( increasing metallic radius )
D. `Al^(3+) lt Mg^(2+) lt Na^(+) lt F^(-)` (increasing ionic size)

Answer

A, B

Explanation

First ionisation energy is the energy required to remove an electron from outermost shell.
Hence , correct order is `B lt C lt O lt N`
For option (b)
Electron gain enthalpy is the energy required to gain an electron in the outermost shell.ltbegt Hence , the correct order is `I lt Br lt F lt CI`
For option (c)
As we move down the group in alkali metal , metallic radius increases `Li lt Na lt K lt Rb`
For option (d)
In case of isoelectronic species increases the ionic size of the species increases and vice-versa
`Al lt Mg^(2+) lt Na^(+) lt F^(-)`