Which of the following does not represent the correct sequence of indicated properties?

Which of the following does not represent the correct sequence of indicated properties?
  1. $\mathrm{Sc}^{3+}>\mathrm{Fe}^{3+}>\mathrm{Mn}^{3+}$; stability of $+3$ oxidation state
  2. $\mathrm{Mn}^{2+} < \mathrm{Ni}^{2+} < \mathrm{Co}^{2+} < \mathrm{Fe}^{2+}$; magnetic moment
  3. $\mathrm{FeO}>\mathrm{CoO}>\mathrm{NiO} ;$, basic character
  4. $\mathrm{Se} < \mathrm{Ti} < \mathrm{Cr} < \mathrm{Mn} ;$ number of oxidation states

Solution

The number of unpaired electrons of the ions in the given choices are $\mathrm{Mn}^{2+}(\mathrm{n}=5) ; \mathrm{Ni}^{2+}(\mathrm{n}=2)$, $\mathrm{Co}^{2+}(\mathrm{n}=3)$ and $\mathrm{Fe}^{2+}(\mathrm{n}=4)$.
The correct sequence of magnetic moments would be $\mathrm{Mn}^{2+}>\mathrm{Fe}^{2+}>\mathrm{Co}^{2+}>\mathrm{Ni}^{2+}$.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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