$\begin{aligned}
& \lambda=900 \mathrm{nm} \quad \text { H-atom }(\mathrm{Z}=1) \
& =9 \times 10^{-5} \mathrm{cm} \
& \mathrm{R}{\mathrm{H}}=10^5 \mathrm{~cm}^{-1} \
& \text { Ryderg eq. }=\frac{1}{\lambda}=\mathrm{R}{\mathrm{H}} \mathrm{Z}^2 \times\left(\frac{1}{\mathrm{n}_1^2}-\frac{1}{\mathrm{n}2^2}\right) \
& \Rightarrow \frac{1}{\lambda \times \mathrm{R}{\mathrm{H}}}=\frac{1}{\mathrm{n}_1^2}-\frac{1}{\mathrm{n}_2^2} \
& \Rightarrow \frac{1}{9 \times 10^{-5} \mathrm{cm} \times 10^5 \mathrm{cm}^{-1}}=\left(\frac{1}{\mathrm{n}_1^2}-\frac{1}{\mathrm{n}_2^2}\right) \
& \Rightarrow \frac{1}{\mathrm{n}_1^2}-\frac{1}{\mathrm{n}_2^2}=\frac{1}{9}
\end{aligned}Itispossiblewhen\mathrm{n}_1=3, \mathrm{n}_2=\inftyPossibleseries:\infty \rightarrow 3$
Heat treatment of muscular pain involves radiation of wavelength of about 900 nm . Which spectral line of H atom is suitable for this? Given :…
JEE Main 2025 — Chemistry Physical Chemistry
2025mcqmedium
Heat treatment of muscular pain involves radiation of wavelength of about 900 nm . Which spectral line of H atom is suitable for this? Given : Rydberg constant RH=105 cm−1, h=6.6×10−34 J s,c=3×108 m/s )
Official previous-year question
Held on 23 Jan 2025 · Verified 6 Jul 2026.
Options
- A
Balmer series, ∞→2
- B
Lyman series, ∞→1
- C
Paschen series, ∞→3
- D
Paschen series, 5→3
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