Question

The first and second ionization enthalpies of lanthanoids are comparable with the element

• A. Chromium
• B. Calcium
• C. Germanium
• D. Cesium
• E. Cadmium

Hint:

Lanthanoids and alkaline earth metals (like calcium) exhibit similar trends in ionization enthalpy, especially as you move across the period.

Answer 1

The Correct Option is B

The first and second ionization enthalpies of lanthanoids (elements from the lanthanide series) are quite high due to the strong effective nuclear charge experienced by the electrons as the atomic size decreases across the series. The trend of ionization enthalpy in lanthanoids is somewhat comparable to calcium because:]
- Calcium (B): Calcium belongs to the alkaline earth metals group and has relatively higher ionization enthalpies, similar to the trend seen in lanthanoids. Both show a similar increase in ionization energy across their respective series due to the increasing nuclear charge.
Thus, the correct answer is (B) Calcium because its ionization enthalpies are comparable to that of the lanthanoids.