PV versus T graph of equal masses of  ${\mathrm{H}}_2,\mathrm{He}$ and  ${\mathrm{O}}_2$ is shown in the figure.

• A

  ‘A’ for ${\mathrm{H}}_2$ , ‘B’ for He, ‘C’ for  ${\mathrm{O}}_2$

• B

  ‘A’ for He, ‘B’ for ${\mathrm{H}}_2$ , ‘C’ for  ${\mathrm{O}}_2$

• C

  ‘A’ for He, ‘B’ for ${\mathrm{O}}_2$ , ‘C’ for  ${\mathrm{H}}_2$

• D

  ‘A’ for ${\mathrm{O}}_2$ , ‘B’ for He, ‘C’ for  ${\mathrm{H}}_2$