JEE Main 2006 Physics question

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature , while Box contains one mole of helium at temperature . 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, , in terms of is

• (1)
• (2)
• (3)
• (4)Correct