Consider the reversible reaction,  ${\mathrm{X}}_2\left(\mathrm{g}\right)\rightleftharpoons 2\mathrm{X}\left(\mathrm{g}\right);$ At equilibrium, number of moles of reactants is equal to that of products. Degree of decomposition of  ${\mathrm{X}}_2$ is

• A

  0.5

• B

  0.4

• C

  0.33

• D

  0.66