Assertion : Potassium ferrocyanide is diamagnetic whereas potassium ferricyanide is paramagnetic. Reason : Crystal field splitting in ferrocyanide ion is greater than that of ferricyanide ion.

• A

  If both assertion and reason are true and reason is the correct explanation of assertion
• B

  If both assertion and reason are true but reason is not the correct explanation of assertion
• Correct answer
  C

  If assertion is true but reason is false
• D

  If both assertion and reason are false.

Solution

Ferrocyanide ion :
In ferrocyanide ion, the oxidation state of $\mathrm{Fe}$ is +2 however in ferricyanide ion, the oxidation number of $\mathrm{Fe}$ is +3 . Generally, the higher the oxidation state of the metal, the greater the crystal field splitting. It means crystal field splitting in ferrocyanide ion is lower than that of ferricyanide ion.

Hence, the correct answer is option: 'C'.