Question

Some energy levels of a molecule are shown in the figure with their wavelengths of transitions. Then:

• A. $λ_3 > λ_2, λ_1 = 2λ_2$
• B. $λ_3 > λ_2, λ_1 = 4λ_2$
• C. $λ_1 > λ_2, λ_2 = 2λ_3$
• D. $λ_2 > λ_1, λ_2 = 2λ_3$

Answer 1

Answer: (D)

$λ_2 > λ_1, λ_2 = 2λ_3$

Answer 2

The energy of a photon is given by $E = \frac{hc}{\lambda}$. Therefore, $\lambda \propto \frac{1}{E}$.

From the diagram:

$\lambda_1$ corresponds to energy difference $E$

$\lambda_2$ corresponds to energy difference $\frac{E}{2}$

$\lambda_3$ corresponds to energy difference $\frac{E}{2}$

Thus $\lambda_2 = 2\lambda_3$ and $\lambda_2 > \lambda_1$.