Atoms and Nuclei · Physics · COMEDK
MCQ (Single Correct Answer)
Which of the following is correct in the case of the Bohr model of atoms?
A. Predicts continuous emission spectra for all atoms
B. Assumes that the angular momentum of electrons is quantised
C. Predicts same emission spectrum for singly ionised neon atom and hydrogen atom
D. Predicts same emission spectrum for singly ionised neon atom and singly ionised helium atom
Which, of the following is true of the Balmer series of the hydrogen spectrum?
a. The series is in the visible region.
b. The entire series falls in the ultraviolet region
c. The entire series falls in the infrared region
d. The series is partly in the visible region and partly in the infrared region
The binding energy per nucleon for $$\mathrm{C}^{12}$$ is $$7.68 \mathrm{~MeV}$$ and that for $$\mathrm{C}^{13}$$ is $$7.47 \mathrm{~MeV}$$. The energy required to remove a neutron from $$\mathrm{C}^{13}$$ is
The distance of closest approach when an alpha particle of kinetic energy $$6.5 \mathrm{~MeV}$$ strikes a nucleus of atomic number 50 is
If an electron in a hydrogen atom jumps from the third orbit to the second orbit, it emits a photon of wavelength $$\lambda$$. When it jumps from the second to the first orbit, the corresponding wavelength of the photon will be
An electron has a mass of $$9.1 \times 10^{-31} \mathrm{~kg}$$. It revolves round the nucleus in a circular orbit of radius $$0.529 \times 10^{-10} \mathrm{~m}$$ at a speed of $$2.2 \times 10^6 \mathrm{~ms}^{-1}$$. The magnitude of its angular momentum is
$$ \text { If the nuclear radius of }{ }^{27} \mathrm{Al} \text { is } 3.6 \text { fermi, the nuclear radius of }{ }^{125} \mathrm{Fe} \text { is } $$
A nucleus with mass number 190 initially at rest emits an alpha particle. If the $$\mathrm{Q}$$ value of the reaction is $$4.5 \mathrm{~MeV}$$, the kinetic energy of the alpha particle is
In a hydrogen atom, if electron is replaced by a particle which is 40 times heavier but has the same charge, then, the ratio of the radius of the first excited state of a normal hydrogen atom to the ground state of the above atom is
The shortest wavelengths of Paschen, Lymen and Balmer series are in the ratio
The radius of a nucleus as measured by electron scattering is $$4.8 \mathrm{~fm}$$. The mass number of nucleus is most likely to be
The ratio of the radii of the nucleus of two element $$\mathrm{X}$$ and $$\mathrm{Y}$$ having the mass numbers 232 and 29 is:
The closest approach of an alpha particle when it make a head on collision with a gold nucleus is $$10 \times 10^{-14} \mathrm{~m}$$, then the kinetic energy of the alpha particle is :
Find the binding energy of the tritium nucleus: [Given: mass of $$1 \mathrm{H}^3=3.01605 \mathrm{~u} ; \mathrm{~m}_{\mathrm{p}}=1.00782 \mathrm{~u} ; \mathrm{~m}_{\mathrm{n}}=1.00866 \mathrm{~u}$$.]
The mass density of a nucleus varies with mass number $$A$$ as
The wavelength of the first line of Lyman series for $$\mathrm{H}$$ - atom is equal to that of the second line of Balmer series for a $$\mathrm{H}$$-like ion. The atomic number $$\mathrm{Z}$$ of $$\mathrm{H}$$-like ion is
The first emission of hydrogen atomic spectrum in Lyman series appears at a wavelength of
The mass number of two nuclei $$\mathrm{P}$$ and $$\mathrm{Q}$$ are 27 and 125 respectively. The ratio of their radii $$R_P: R_Q$$ is given by:
In a nuclear reaction 2 deuteron nuclei combine to form a helium nucleus. The energy released in $$\mathrm{MeV}$$ will be: (Given mass of deuteron $$=2.01355 \mathrm{~amu}$$. and mass of helium nucleus $$=4.0028 \mathrm{~amu}$$.
A particle at rest decays in to two particles of mass $$m_1$$ and $$m_2$$ and move with velocities $$v_1$$ and $$v_2$$. The ratio of their de Broglie wave length $$\frac{\lambda_1}{\lambda_2}$$ is:
The ground state energy of hydrogen atom is $$-13.6 \mathrm{~eV}$$. If the electron jumps from the $$3^{\text {rd }}$$ excited state to the ground state then the energy of the radiation emitted will be:
In the head-on collision of two alpha particles $$\alpha_1$$ and $$\alpha_2$$ with the gold nucleus, the closest approaches are 31.4 fermi and 94.2 fermi respectively. Then the ratio of the energy possessed by the alpha particles $$\alpha_2 / \alpha_1$$ is:
Which of the following statement is true when a gamma decay occurs from the nucleus of an atom?
During $$\alpha$$-decay, atomic mass of parent nuclei is
Which of the following series spectrum of hydrogen atom lies in ultraviolet region?
The wavelength of the second line of Balmer series is 486.4 nm. What is the wavelength of the first line of Lyman series?
The Lyman series of a hydrogen atom belongs in which category
If an electron in hydrogen atom jumps from an orbit of level $$n=3$$ to an orbit at level $$n=2$$, emitted radiation has a frequency of
(R = Rydberg's constant and c = velocity of light)
Ba-122 has half-life of 2 min. Experiment has to be done using Ba-122 and it takes 10 min to set up the experiment. It initially 80 g at Ba-122 was taken, how much Ba was left when experiment was started?
When the speed of light becomes $$\frac{2}{3}$$ of its present value, then the energy released in a given atomic explosion would
An electron of an atom transits from $$n_1$$ to $$n_2$$. In which of the following maximum frequency of photon will be emitted?
Two protons are kept at a separation of 40 $$\mathop A\limits^o $$. F$$_n$$ is the nuclear force and F$$_e$$ is the electrostatic force between them. Then,
Two radioactive materials X$$_1$$ and X$$_2$$ have decay constant 5$$\lambda$$ and $$\lambda$$, respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X$$_1$$ to X$$_2$$ will be $$1/e$$ after a time