Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at a temperature To, while box B contains one mole of helium at temperature (7/3) T₀. The boxes are then put into thermal contact with each other and heat flows between them until the gases reach a common final temperature (Ignore the heat capacity of boxes). Then the final temperature of the gases, T_f, in terms of T₀ is :

• A

  ${\mathrm{T}}_{\mathrm{f}}=\frac{3}{2}{\mathrm{T}}_0$

• B

  ${\mathrm{T}}_{\mathrm{f}}=\frac{5}{2}{\mathrm{T}}_0$

• C

  ${\mathrm{T}}_{\mathrm{f}}=\frac{3}{7}{\mathrm{T}}_0$

• D

  ${\mathrm{T}}_{\mathrm{f}}=\frac{7}{3}{\mathrm{T}}_0$