Answer
Per atom $\Delta K=3.11\times 10^{-22}J$
Work Step by Step
Per atom $\Delta K=\Delta E_{internal}/N $ where $N$ is the total number of atoms.
We have, $n=2 moles$ so, $N= 2\times6\times10^{23}=12\times10^{23} atoms$
Hence, Per atom $\Delta K=\frac{374}{12\times10^{23}}=3.11\times10^{-22} J$
