The stability of the following alkali metal chlorides follows the order:

Options

A. LiCl `gt` KCl `gt` NaCl `gt` CsCl
B. CsCl `gt` KCl `gt` NaCl `gt` LiCl
C. NaCl `gt` KCl `gt` LiCl `gt` CsCl
D. KCl `gt` CsCl `gt` NaCl `gt` LiCl.

Answer

D

Explanation

Standard enthalpies of formation of alkali metal chlorides, are
`DeltaH_(f)^(@) (LiCl) = - 408.8 " kJ mol" ^(-1)`
`DeltaH_(f)^(@) (NaCl) = - 411.15 " kJ mol" ^(-1)`
`DeltaH_(f)^(@) (CsCl) = - 433 " kJ mol" ^(-1)`
`DeltaH_(f)^(@) (KCl) = - 436 " kJ mol" ^(-1)`.
More the magnitude of enthalpy of formation (heat evolved when one mole of the compound is formed from the elements) more the stability of the compound. Therefore order of stabilities is
`LiCl lt NaCl lt CsCl lt KCl`.