AP EAMCET202315 May 2023Morning ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
Consider the following two statements Statement I: Among Mg , Al , Mg ²⁺, Al ³⁺ the one having smallest size is Al ³⁺Statement II: Eu is having exceptionally high atomic radii among lanthanide elements The correct answer is
Options
- ABoth statements I and II are correct
- BBoth statements I and II are not correct
- CStatement I is correct but statement II not correct
- DStatement I is not correct but statement II is correct
Correct answer
C. Statement I is correct but statement II not correct
Step-by-step solution
Al atom is smaller than Mg atom as Al lies to the right of Mg and it has greater effective nuclear charge. A cation is smaller than its parent atom so Al ³⁺ is smaller than Al and therefore Al ³⁺ is smallest in size. Thus, statement I is correct. Among lanthanides there is a gradual decrease in the atomic and ionic radii as we move from left to right due to lanthanoid contraction. As per the latest data from rsc.org; the atomic radii of Sm, Eu and Gd are:- aligned & Sm =236 pm , 185 pm (covalent) & Eu =235 pm , 183