question_answer

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature to, while box B contains one mole of helium at temperature (7/3)\[{{T}_{0}}\]. 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\[{{T}_{0}}\]is                                                        [AIEEE 2006]

A)  \[{{T}_{f}}=\frac{3}{7}{{T}_{0}}\]   

B)       \[{{T}_{f}}=\frac{7}{3}{{T}_{0}}\]

C)  \[{{T}_{f}}=\frac{3}{2}{{T}_{0}}\]   

D)       \[{{T}_{f}}=\frac{5}{2}{{T}_{0}}\]

Correct Answer: C

Solution :

[c] Here, change in internal energy of the system is zero. i.e., increase in internal energy of one is equal to decrease in internal energy of other.

Now,