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Two moles of an ideal monatomic gas initially at temperature T0 are combined with four moles of another ideal monatomic gas initially at temperature 2T0. Assuming no heat loss, the equilibrium temperature of the final mixture is

1. 5T0/3
2. 3T0/2
3. 4T0/3
4. 5T0/4

Correct answer: 5T0/3

Solution

With the same Cv, T = (n1*T1 + n2*T2)/(n1 + n2) = (2*T0 + 4*2T0)/6 = 10T0/6 = 5T0/3.

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