Question

For a hypothetical H-like atom, which follows Bohr model, some spectral lines are observed as shown. If it is known that line E belong to visible region., then the line, which possibly belong to U.V. region is/are? $\left(\right.n_{1}$ is not necessarily the ground state)

• A. B and D
• B. D only
• C. C only
• D. A only

Answer 1

Answer: (D)

Line E belong to visible so $n_{1}$ will be 2.



For E, $\Delta E=+13.6\times z^{2}\left(\frac{1}{4} - \frac{1}{9}\right)=13.6\times z^{2}\times 0.138$

For D, $\Delta E=13.6\times z^{2}\left(\frac{1}{9} - \frac{1}{36}\right)=13.6\times z^{2}\times 0.083$

For C, $\Delta E=13.6\times z^{2}\left(\frac{1}{16} - \frac{1}{36}\right)=13.6\times z^{2}\times 0.034$

For A, $\Delta E=13.6\times z^{2}\left(\frac{1}{4} - \frac{1}{25}\right)=13.6\times z^{2}\times 0.21$

For B, $\Delta E=13.6\times z^{2}\left(\frac{1}{9} - \frac{1}{25}\right)=13.6\times z^{2}\times 0.07$

For $\Delta E$ for A is larger than that of E, so it means line A belong to U.V. region.