| (1) $220$ | (2) $330$ | (3) $400$ | (4) $500$ |
\textbf{174.} In the hydrogen atom in the Balmer series ($n' = 2$), the longest wavelength of the emitted light is how many nanometers?
$$\left[R = 0.01\ (\text{nm})^{-1}\right]$$
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(1) $220$ & (2) $330$ & (3) $400$ & (4) $500$
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