Chemistry - Atomic Structure Question with Solution | TestHub

For a hydrogen-like ion, the kinetic energy is $K=13.6Z^2/n^2\mathrm{eV}$. Here $Z=3$ and the first excited state has $n=2$, so

$$K=13.6\frac{3^2}{2^2}=30.6\mathrm{eV}.$$

*Editorial correction:* the question PDF says "total energy ... is 13.6 eV" without a minus sign. Bound-state total energy is $-13.6\mathrm{eV}$ in hydrogen's ground state; "magnitude" makes the intended positive datum precise.