Bohr S Model Of Hydrogen Atom

The question asks which series of transitions in the spectrum of the hydrogen atom falls in the visible region. Let's analyze the options:

1. The Lyman series involves transitions where an electron falls to the n=1 orbit from higher orbits (n > 1). The radiation emitted is in the ultraviolet region, not visible.
2. The Balmer series is characterized by electron transitions from higher orbits (n > 2) to the n=2 orbit. Importantly, this series emits radiation in the visible part of the electromagnetic spectrum. These transitions account for the visible hydrogen emission lines.
3. The Paschen series consists of transitions involving electrons dropping to the n=3 orbit from higher orbits (n > 3). These transitions produce infrared radiation, not visible light.
4. The Brackett series involves transitions where electrons fall to the n=4 orbit from higher orbits (n > 4). Like the Paschen series, this series also emits infrared radiation.

Based on the descriptions above, we can conclude that the Balmer series is the correct answer as it is the only series that falls within the visible spectrum.

Conclusion: \text{Balmer series falls in the visible region of the hydrogen emission spectrum.}