NEET2026ChemistryClassification of Elements and Periodicity in PropertiesActual
Identify the incorrect statement from the following :
Options
- AThe largest and the smallest species among Mg, Mg ²⁺ , Al and Al ³⁺ are Al and Mg ²⁺ , respectively.
- BThe IUPAC name of the element with atomic number 107 is Unnilseptium.
- CThe similarity in behaviour of Li with Mg is referred to as 'diagonal relationship'.
- DThe oxidation state and covalency of Al in [ AlCl ( H ₂ O )₅]²⁺ are 3 and 6 respectively.
Correct answer
A. The largest and the smallest species among Mg, Mg ²⁺ , Al and Al ³⁺ are Al and Mg ²⁺ , respectively.
Step-by-step solution
Atomic radius decreases across a period from left to right, so the atomic radius of Mg is greater than that of Al . For isoelectronic species, the ionic radius decreases with an increase in nuclear charge. Both Mg ²⁺ and Al ³⁺ have 10 electrons, but Al ³⁺ has a higher nuclear charge ( Z=13 ) compared to Mg ²⁺ ( Z=12 ), making Al ³⁺ smaller than Mg ²⁺ . Cations are always smaller than their respective parent atoms. Therefore, the overall decreasing order of size is Mg > Al > Mg ²⁺ > Al ³⁺ . The largest species is Mg