Q79 (2024)
Identify the incorrect statement from the following:
- (1) The IUPAC name of the element with atomic number 107 is Unnilseptium.
- (2) The largest and the smallest species among $Mg$, $Mg^{2+}$, $Al$ and $Al^{3+}$ are $Al$ and $Mg^{2+}$ respectively.
- (3) The similarity in behaviour of Li with Mg is referred to as 'diagonal relationship'.
- (4) The oxidation state and covalency of Al in $[AlCl(H_2O)_5]^{2+}$ are +3 and 6, respectively.
### Related Formula
$$\text{Atomic/Ionic Radii Order: } Mg > Al > Mg^{2+} > Al^{3+}$$
### Core Logic
Comparing species:
Largest atomic species is $Mg$ (not $Al$, since radius decreases across period).
Smallest species is $Al^{3+}$ (highest effective nuclear charge among isoelectronic ions).
Thus, statement (2) is incorrect.
### Step 1: Conclusion
Incorrect statement is (2).
### Pattern Recognition
Atomic size decreases across a period ($Mg > Al$). Isoelectronic cations size decreases with higher positive charge ($Mg^{2+} > Al^{3+}$).
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Classification of Elements and Periodicity in Properties
