Atoms
16 NEET Physics previous year questions on Atoms — options free on every question; 2 include the answer & explanation free, the rest unlock with PYQ Pass.
A particle of mass m is moving around the origin with a constant force F pulling it towards the origin. If Bohr model is used to describe its motion, the radius of the \({\mathrm{n}}^{\text{th }}\) orbit and the particle's speed v in the orbit depend on n as
[NEET 2025]
\(\mathrm{r}\propto {\mathrm{n}}^{2/3};\mathrm{v}\propto {\mathrm{n}}^{1/3}\)
Given, force is constant
\(F=\frac{m{v}^{2}}{r}\)
\(\Rightarrow \frac{{v}^{2}}{r}=\text{constant}\)
\(\Rightarrow r\propto {v}^{2}\ldots \left(1\right)\)
\(L=mvr=\frac{nh}{2\pi }\) ...(2)
⇒ on solving equation (1) and equation (2)
\(v\propto {n}^{1/3}\) and \(r\propto {n}^{2/3}\)
In the first excited state of hydrogen atom, the energy of its electron is –3.4 eV. The radial distance of the electron from the hydrogen nucleus in this case is approximately :
(Take 1 eV = 1.6 × 10–19 J, e = 1.6 × 10–19 C and \(\frac{1}{4\pi {\epsilon }_{0}}\) = 9 × 109 N m2/C2)
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Match List I with List I
| List I (Electromagnetic wave) | List II (Production) |
| A. Microwave | I. Electrons in atoms emit light when they move from a higher energy level to a lower energy level |
| B. Visible light | II. Radioactive decay of nucleus |
| C. Gamma rays | III. Vibration of atoms and molecules |
| D. Infra-red rays | IV. Klystron valve or magnetron valve |
Choose the correct answer from the options given below:
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The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region?
[JEE Main 2021, 17 Mar (Shift 2)]
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The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from \(n=2\) to \(n=1\) state is:
[JEE Main 2021, 25 Feb (Shift 2)]
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The radius of electron's second stationary orbit in Bohr's atom is \(R\). The radius of 3rd orbit will be:
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The radius of inner most orbit of hydrogen atom is \(5.3 \times 10^{-11} \mathrm{~m}\). What is the radius of third allowed orbit of hydrogen atom?
[NEET 2023]
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Speed of an electron in Bohr's \(7^{\text {th }}\) orbit for Hydrogen atom is \(3.6 \times 10^6 m / s\). The corresponding speed of the electron in \(3^{\text {rd }}\) orbit, in \(m / s\) is:
[JEE Main 2023, 30 Jan (Shift 1)]
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The energy required to break one bond in DNA is \( 10^{-20} \mathrm{~J} \). This value in \( \mathrm{eV} \) is nearly.
[NEET 2020]
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Given below are two statements:
Statement I : Atoms are electrically neutral as they contain equal number of positive and negative charges.
Statement II : Atoms of each element are stable and emit their characteristic spectrum.
In the light of the above statements, choose the most appropriate answer from the options given below:
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An electron of a hydrogen like atom, having \(Z=4\), jumps from \(4^{\text {th }}\) energy state to \(2^{\text {nd }}\) energy state, The energy released in this process, will be:
(Given \(R c h=13.6 eV\) ) Where \(R=\) Rydberg constant, \(c=\) Speed of light in vacuum, \(h=\) Planck's constant.
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For which one of the following, Bohr model is not valid?
[NEET 2020]
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The total energy of an electron in the \( \mathrm{n}^{\text {th }} \) stationary orbit of the hydrogen atom can be obtained by.
[Re-NEET 2020]
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The minimum wavelength of X-rays produced by an electron accelerated through a potential difference of \(V\) volts is proportional to :
[NEET 2023]
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Match List I with List II.
| List-I | List-II | ||
| (Spectral Lines of Hydrogen for transitions from) | (Wavelengths(nm)) | ||
| 1. | \({n}_{2}=3\mathrm{to}{n}_{1}=2\) | P. | 410.2 |
| 2. | \({n}_{2}=4\mathrm{to}{n}_{1}=2\) | Q. | 434.1 |
| 3. | \({n}_{2}=5\mathrm{to}{n}_{1}=2\) | R. | 656.3 |
| 4. | \({n}_{2}=6\mathrm{to}{n}_{1}=2\) | S. | 486.1 |
Choose the correct answer from the options given below :
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