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7. Redox reactions — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistry7. Redox reactions1 Mark
MCQ
The oxidation number of $Cr$ in ${K_2}C{r_2}{O_7}$ is
  • ✓
    $+6$
  • B
    $-7$
  • C
    $+2$
  • D
    $-2$
✓

Answer

Correct option: A.
$+6$
(a) $\mathop {{K_2}C{r_2}{O_7}}\limits^{ * \,\,} $

$2 + 2x - 2 \times 7 = 0$; $2x - 14 + 2 = 0$

$2x = 12$; $x = \frac{{12}}{2} = + 6$.

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