Chemistry · Periodic trends in properties of elements: atomic and ionic radii, ionization enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity
Assertion The mobility of sodium ion is lower than that of potassium ion. Reason
Assertion The mobility of sodium ion is lower than that of potassium ion. Reason The ionic mobilities depend on the effective radius of the ion. Read the above assertion and reason and choose the correct option regarding ¡t.
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Assertion is incorrect but Reason is correct
Step-by-step solution
Sodium ion (Na+) has a smaller bare ionic radius than potassium ion (K+), but in water, Na+ is more strongly hydrated, resulting in a larger effective (hydrated) radius. Since ionic mobility decreases with increasing effective radius, Na+ has lower mobility than K+. The reason correctly states that ionic mobilities depend on the effective radius of the ion, and this explains the assertion.