Q54 / 180 · JIPMER 2016 · Chemistry

Consider the reaction, $\mathrm{H}_2+X_2 \longrightarrow 2 \mathrm{H} X$, where $X$ is halogen. The reactivity of halogens decrease in the order of

  • A
    $\mathrm{Cl}_2\gt\mathrm{F}_2\gt\mathrm{Br}_2\gt\mathrm{I}_2$
  • B
    $\mathrm{I}_2\gt\mathrm{Br}_2\gt\mathrm{F}_2\gt\mathrm{Cl}_2$
  • Correct answer
    C
    $\mathrm{F}_2\gt\mathrm{Cl}_2\gt\mathrm{Br}_2\gt\mathrm{I}_2$
  • D
    $\mathrm{I}_2\gt\mathrm{Br}_2\gt\mathrm{Cl}_2\gt\mathrm{F}_2$

Solution

$\mathrm{H}-\mathrm{H}+\mathrm{X}-\mathrm{X} \longrightarrow 2 \mathrm{HX}$, where $X=$ halogen. The correct decreasing order of reactivity of halogen molecule towards $\mathrm{H}_2$ is $\mathrm{F}_2\gt\mathrm{Cl}_2\gt\mathrm{Br}_2\gt\mathrm{I}_2$.

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

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