Two perfect monoatomic gases at absolute temperature `T_(1)` and `T_(2)` are mixed. There is no loss of energy. Find the temperature of the mixture if the number of moles in the gases are` n_(1)` and `n_(2)`.
A. `(T_(1)+T_(2))/(n_(1)+n_(2))`
B. `(T_(1))/(n_(1))+(T_(2))/(n_(2))`
C. `(n_(2)T_(1)+n_(1)T_(2))/(n_(1)+n_(2))`
D. `(n_(1)T_(1)+n_(2)T_(2))/(n_(1)+n_(2))`