MCQ
A first row transition metal with highest enthalpy of atomisation, upon reaction with oxygen at high temperature forms oxides of formula $\mathrm{M}_2 \mathrm{O}_{\mathrm{n}}$ (where $\mathrm{n}=3,4,5$ ). The 'spin-only' magnetic moment value of the amphoteric oxide from the above oxides is. . . . . . ..$\mathrm{BM}$ (near integer)

(Given atomic number: $\mathrm{Sc}: 21, \mathrm{Ti}: 22, \mathrm{~V}: 23$, $\mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26, \mathrm{Co}: 27, \mathrm{Ni}: 28, \mathrm{Cu}: 29$, $\mathrm{Zn}: 30)$

  • A
    $1$
  • B
    $2$
  • C
    $3$
  • $0$

Answer

Correct option: D.
$0$
d
$\mathrm{V}$ ' has highest enthalpy of atomisation ( $515 \mathrm{~kJ} / \mathrm{mol}$ ) among first row transition elements.

$\mathrm{V}_2 \mathrm{O}_5$

Here ' $\mathrm{V}$ ' is in $+5$ oxidation state

$\mathrm{V}^{-5} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{p}^6 3 \mathrm{~s}^2 3 \mathrm{p}^6 \text { (no unpaired electrons) }$

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