Answer:
14657.32 J
Explanation:
Given Parameters ;
Number of moles mono atomic gas A , Â n 1 Â = Â 4 .2 mol
Number of moles mono atomic gas B , Â n 2 Â = Â 3.2mol
Initial energy of gas A , Â K A Â = Â 9500 Â J
Thermal energy given by gas A to gas B ,  Δ K  =  600 J
Gas constant  R  = 8.314  J / molK
Let  K B  be the initial energy of gas B.
Let T be the equilibrium temperature of the gas after mixing.
Then we can write the energy of gas A after mixing as
(3/2)n1RT = KA - ΔK
⟹ (3/2) x 4.2 x 8.314 x T = 9500 - 600
T = (8900 x 3 )/(2x4.2x8.314) = 382.32 K
Energy of the gas B after mixing can be written as
(3/2)n2RT = KB + ΔK
⟹ (3/2) x 3.2 x 8.314 x 382.32 = KB + 600
⟹ KB = [(3/2) x 3.2 x 8.314 x 382.32] - 600
⟹ KB = 14657.32 J