Q49 / 170 · Manipal (MET) 2017 · Chemistry

$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ on heating with aqueous caustic soda gives

  • Correct answer
    A
    $\mathrm{CrO}_4^{2-}$
  • B
    $\mathrm{Cr}(\mathrm{OH})_2$
  • C
    $\mathrm{Cr}(\mathrm{OH})_3$
  • D
    $\mathrm{Cr}_2 \mathrm{O}_7^{2-}$

Solution

$\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}$ on heating with aqueous alkalies gives chromates $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7+2 \mathrm{NaOH} \longrightarrow \mathrm{~K}_2 \mathrm{CrO}_4+\mathrm{Na}_2 \mathrm{CrO}_4+\mathrm{H}_2 \mathrm{O}$

Hence, the correct answer is option: 'A'.

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