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AP EAMCET · Chemistry · Chemical Bonding and Molecular Structure

The correct order of increasing ionic character among \(\mathrm{LiH}, \mathrm{NaH}, \mathrm{KH}, \mathrm{RbH}, \mathrm{CsH}\) is

  1. A \(\mathrm{LiH} < \mathrm{NaH} < \mathrm{CsH} < \mathrm{KH} < \mathrm{RibH}\)
  2. B \(\mathrm{LiH} < \mathrm{NaH} < \mathrm{KH} < \mathrm{RibH} < \mathrm{CsH}\)
  3. C \(\mathrm{PbH} < \mathrm{CsH} < \mathrm{NaH} < \mathrm{KH} < \mathrm{LiH}\)
  4. D \(\mathrm{NaH} < \mathrm{CsH} < \mathrm{Rb}-\mathrm{H} < \mathrm{LiH} < \mathrm{KH}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\mathrm{LiH} < \mathrm{NaH} < \mathrm{KH} < \mathrm{RibH} < \mathrm{CsH}\)

Step-by-step Solution

Detailed explanation

According to Fajan's rule, the size of the cations increase down a group and also, the increase in size of an atom increases the ionic molecules formed. Caesium being lowest down the group has most ionic character, followed by rubidium, potassium, sodium and lithium…