Atoms and Nuclei

An electron in hydrogen atom makes a transition n₁ → n₂ where n₁ and n₂ are principal quantum number of the two states. Assuming Bohr’s model to be valid the time period of the electron in the initial state is eight times that in the final state. The possible values of n₁ and n₂ are

An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function 2.75 eV. If the stopping potential of the photoelectron is 10 V, the value of n is

An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be: (m is the mass of electron, R, Rydberg constant and h Planck’s constant)

Which of the following is true for number of spectral lines in going from Lyman series to Pfund series?

What is the wavelength of light for the least energetic photon emitted in the Lyman series of the hydrogen spectrum. (take, hc=1240 eV-nm)

Given the value of Rydberg constant is 10⁷ m⁻¹, the wave number of the last line of the Balmer series in hydrogen spectrum will be

Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube. The cut-off wavelength (λ₀) of the emitted X-ray is

If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength λ. When it jumps from the 4th orbit to the 3rd orbit, the corresponding wavelength of the photon will be

Number of spectral lines in hydrogen atom is

The excitation potential of hydrogen atom in the first excited state is

The first line in Lyman series has wavelength λ. The wavelength of the first line in Balmer series is

The ionisation energy of hydrogen is 13.6 eV. The energy of the photon released when an electron jumps from the first excited state (n=2) to the ground state of hydrogen atom is

For principal quantum number n=3, the possible values of orbital quantum number l are

If, an electron in hydrogen atom jumps from an orbit of level n=3 to an orbit of level n=2, emitted radiation has a frequency (R = Rydberg’s constant, c = velocity of light)

The Rutherford scattering experiment proves that an atom consists of

The sodium nucleus ₁₁Na²³ contains

The wavelength of light emitted from second orbit to first orbit in a hydrogen atom is

In Moseley’s law √ν = a(z-b), the values of the screening constant for K-series and L-series of X-rays are respectively

The Kα X-ray of molybdenum has a wavelength of 71 x 10⁻¹² m. If the energy of a molybdenum atom with K- electron removed is 23.32 keV, then the energy of molybdenum atom when an L-electron removed is
(hc = 12.42 x 10⁻⁷ eV)

The ratio of speed of an electron in ground state in Bohr’s first orbit of hydrogen atom to velocity of light in air (c ) is

Light emitted during the de excitation of electron from n=3 to n=2, when incident on a metal, photoelectrons are just emitted from that metal. In which of the following de excitations photoelectric effect is not possible?

The ionisation energy of an electron in the ground state of helium atom is 24.6 eV. The energy required to remove both the electron is

The radius of the first orbit of the hydrogen atom is a₀. The radius of the second orbit will be

The total energy of electron in the ground state of hydrogen atom is -13.6 eV. The kinetic energy of an electron in the first excited state is

Spectrum of X-rays is

In a Rutherford scattering experiment when a projectile of charge Z₁ and mass M₁ approaches a target nucleus of charge Z₂ and mass M₂, the distance of closest approach is r. The energy of the projectile is

Which series of hydrogen spectrum corresponds to ultraviolet region?

The ratio of volumes of nuclei (assumed to be in spherical shape) with respective mass number 8 and 64 is

The energy of a hydrogen atom in the ground state is -13.6 eV. The energy of a He⁺ ion in the first excited state will be

The order of radius of the nucleus of an atom is

If the series limit of Lyman series for hydrogen atom is equal to the series limit of Balmer series for a hydrogen like atom, then atomic number of this hydrogen like atom is

Which pair is isotonic?

The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is

Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelengths λ₁:λ₂ emitted in the two cases is

The de-Broglie wavelength of an electron in the first Bohr orbit is

In Bohr model of hydrogen atom, the force on the electron depends on the principal quantum number (n) as

The transition from the state 3n = 3 to n = 1 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from:

One milligram of matter on convertion into energy will give

The wavelength of Kα line in copper is 1.5Å. The ionisation energy of K electron in copper is

When alpha particles captures and electron, then it becomes a

The ratio of longest wavelength corresponding to Lyman and Blamer series in hydrogen spectrum is

The wavelength of first line of Balmer series is 6563Å. The wavelength of first line of Lyman series will be

Which of the following transitions will have highest emission wavelength?

The electron of a hydrogen atom revolves round the proton in a circular nth orbit of radius
r(n) = ε₀n²h² / (πme²) with a speed v(n) = e² / 2ε₀nh.
The current due to the circulating charge is proportional to

When the wave of hydrogen atom comes from infinity into the first orbit, the value of wave number is

If 10000 V is applied across an X-ray tube, what will be the ratio of de-Broglie wavelength of the incident electrons to the shortest wavelength X-ray produced?
(e/m for electron = 1.8 x 10¹¹ C kg⁻¹)

If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li⁺⁺ is

If the ionisation energy for the hydrogen atom is 13.6 eV, the energy required to excite it from the ground state to the next higher state is nearly

Complete the reaction: ₀n¹ + ₉₂U²³⁵ → ₅₆Ba¹⁴⁴ + …….. + 3n

The Bohr model of atoms

In the reaction ₁²H+₁³H+₂⁴He+₀¹n, if the binding energies of ₁²H,₁³H and ₂⁴He are respectively a,b and c (in MeV), then the energy (in MeV) released in this reaction is

The total energy of an electron in the first excited state of hydrogen atom is about -3.4 eV. Its kinetic energy in this state is

If M (A; Z), Mp and Mn denote the masses of the nucleus zXᴬ, proton and neutron respectively in units of u (1u = 931.5 MeV/c) and BE represents its bonding energy in MeV, then

Two nuclei have their mass numbers into the ratio of 1:3. The ratio of their nucleus densities would be

If λ₁ and λ₂ are the wavelengths of the first members of the Lyman and Paschen series respectively, then the λ₁ : λ₂ is

The mass of a ⁷₃ Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of ⁷₃ Li nucleus is nearly

The binding energy per nucleon in deuterium and helium nuclei are 1.1 MeV and 7.0 MeV, respectively. When two deuterium nuclei fuse to form a helium nucleus the energy released in the fusion is:

If the number of radius of ²⁷Al is 3.6 Fermi, the approximate nuclear radius of ⁶⁴Cu in Fermi is:

Two nuclei are said to be mirror nuclei of

The atomic number of the most common element in nuclear fusion is

The order of distance of an electron revolving in an atom from nucleus is

In which case positive work has to be done in separating them?

The emission line of Lyman corresponds to the absorption line in laboratory temperature. The emission line of Balmer at room temperature

The operation of a nuclear reactor is said to be critical, if the multiplication factor(k) has a value

The binding energy of deuteron is 2.2 MeV and that of ₂⁴He is 28 MeV. If two deuterons are fused to form one ₂⁴He then the energy released is

The radius of germanium nuclide is measured to be twice the radius of ₄⁹Be. The number of nucleons in Ge are

When ₃Li⁷ nuclei are bombarded by protons, and the resultant nuclei are ₄Be⁸, the emitted particles will be

If the binding energy of the nucleon in ₃⁷Li and ₂⁴He nuclei are 5.60 MeV and 7.06 MeV respectively, then in the reaction:
p+₃⁷Li→2 ₂⁴He, energy of proton must be

In Raman effect, Stoke’s lines are spectral lines having

The volume of a nucleus is directly proportional to

Which of the following does not increase regularly?

Bohr’s postulates quantizes

In the Bohr’s model of hydrogen atom, the ratio of the kinetic energy to the total energy of the electron in nth quantum state is

Mass defect is known as

Rutherford’s α-scattering experiment concludes that

Calculate power output of ₉₂²³⁵U reactor, if it takes 30 days to use up 2 kg of fuel, and if each fission gives 185 MeV of useable energy. Avogadro’s number = 6 x 10²³/mol?

If the nucleus ₁₃Al²⁷ has nuclear radius of about 3.6 fm, then ₃₂Te¹²⁵ would have its radius approximately as

Which of the following transitions in hydrogen atoms emit photons of highest frequency?

Two nuclei have their mass number in the ratio of 1:3. The ratio of their nuclear densities would be

The ratio of minimum wavelengths of Lyman and Balmer series will be

The ratio of the nuclear radii of elements with mass numbers 216 and 125 is

The most stable particle in Baryon group is

The nuclear radius of a certain nucleus is 7.2 fm and it has a charge of 1.28 x 10⁻¹⁷ C. The number of neutrons inside the nucleus is

The nuclei of which one of the following pairs of nuclei are isotones?

Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr’s theory, the spectral lines emitted by hydrogen will be

In which of the following systems will the radius of the first orbit (n=1) be minimum?