CBSE Questions for Class 12 Medical Physics Atoms Quiz 12 - MCQExams.com

In the figure six lines of emission spectrum are shown. Which of them will be absent in the absorbtion spectrum.


74448.jpg
  • 1,2,3
  • 1,4,6
  • 4,5,6
  • 1,2,3,4,5,6
According to drop model of nucleus which of the following cannot be explained ?
  • Fission
  • Fusion
  • $$\alpha-$$ spectrum
  • All of these
A particle moving with a velocity $$\dfrac{1}{10}th$$ of light will cross a nucleus in about:
  • $$10^{-8}sec$$
  • $$10^{-12}sec$$
  • $$10^{-47}sec$$
  • $$10^{-21}sec$$
Stability of half filled sub-shell is caused by :
  • exchange energy
  • greater spin above
  • both $$(a)$$ and $$(b)$$
  • none of the above
Who proved that atoms had a nucleus? 
  • Ernest Rutherford
  • James Chadwick
  • J.J. Thomson
  • None of these
The mass of an electron in motion depends upon :
  • direction fotion
  • its velocity
  • initiial mass of $$e^-$$
  • its shell number
In Bohr's radius is $$R_0$$ then radius of $$3^{rd}$$ orbit of hydrogen atom will be :
  • $$3R_0$$
  • $$6R_0$$
  • $$9R_0$$
  • $$12R_0$$
Mark out the incorrect statement:
  • A free neutron can transform itself into photon
  • A free proton can transform itself into neutron
  • In beta minus decay, the electron originates from nucleus
  • All of the above
Taking the Bohr radius as $$a_0 = 53 pm$$, the radius of $$Li^{++}$$ ion in its ground state, on the basis of Bohr's model, will be about
  • $$53 pm $$
  • $$27 pm $$
  • $$18 pm $$
  • $$13 pm $$
Which of the following statements about Rutherford’s model of atom are correct?
(i) Proposed that nearly all the mass of an atom resides in the nucleus.
(ii) Established that the $$\alpha$$–particles are four times as heavy as a hydrogen atom.
(iii) Considered the nucleus as positively charged.
(iv) Agreed with Thomson’s model.
  • (i) and (iii)
  • (ii) and (iii)
  • (i) and (iv)
  • only (i)
Rutherford's $$\alpha-$$particle scattering experiment discovered
  • Electron
  • Proton
  • Atomic nucleus
  • Neutron
In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly proportional to ($$n=$$ principle quantum number)
  • $$n^{-1}$$
  • $$n$$
  • $$n^{-2}$$
  • $$n^{2}$$
The Balmer series for the H-atom can be observed
  • if we measure the frequencies of light emitted when an excited atom falls to the ground state.
  • if we measure the frequencies of light emitted due to transitions between excited states and the first excited state.
  • in any transition in a H - atom
  • as a sequence of frequencies with the higher frequencies getting closely packed.
According to Bohr's theory the radius of electron in an orbit described by principle quantum number $$n$$ and atomic number $$Z$$ is proportional to
  • $$Z^{2}n^{2}$$
  • $$\dfrac{Z^{2}}{n^{2}}$$
  • $$\dfrac{Z^{2}}{n}$$
  • $$\dfrac{n^{2}}{Z}$$
According to de-Broglie wavelength for electron in an orbit of hydrogen atom is $$10^{-9}\ m$$. The principle quantum number for this electron is 
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
Which of the following is true.
  • Lyman series is a continuous spectrum
  • Paschen series is a line spectrum in the infrared
  • Balmer series is a line spectrum in the ultraviolet
  • The spectral series formula can be derived from the Rutherford model of the hydrogen atom
The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the
  • Balmer series
  • Pfund series
  • Paschen series
  • Lyman series
The splitting of line into groups under the effect of electric or magnetic field is called
  • Zeeman's effect
  • Bohr's effect
  • Heisenberg's effect
  • Magnetic effect
In bohr's model, if the atomic radius of the first orbit is $$r_0$$, then the radius of the fourth orbit is 
  • $$r_0$$
  • $$4r_0$$
  • $$r_0/16$$
  • $$16r_0$$
To explain his theory, Bohr-used
  • Conservation of linear momentum
  • Conservation of angular momentum
  • Conservation of quantum frequency
  • Conservation of energy
Which one of these is non-divisible
  • Nucleous
  • Photon
  • Proton
  • Atom
Radius of the first orbit of the electron in a hydrogen atom is $$0.53\ A^o$$. So, the radius of the third orbit will be 
  • $$2.12\ A^o$$
  • $$4.77\ A^o$$
  • $$1.06\ A^o$$
  • $$1.59\ A^o$$
The fact that photons carry energy was established by
  • Doppler's effect
  • Compton's effect
  • Bohr's theory
  • Diffraction of light
Which of the following spectral series in hydrogen atom give spectral line of $$4860\ A^o$$
  • Lyman
  • Balmer
  • Paschen
  • Brackett
For principal quantum number $$n=3$$, the possible values of orbital quantum number $$'I$$ are 
  • $$1, 2, 3$$
  • $$0, 1, 2, 3$$
  • $$0, 1, 2$$
  • $$-1, 0, +1$$
In Bohr's model of hydrogen atom, which of the following pairs of quantities are quantized
  • Energy and linear momentum
  • Linear and angular momentum
  • Energy and angular momentum
  • None of these
The boher model of atoms
  • Assume that the angular momentum of electrons is quantized
  • Uses Einstein's photo electric equation
  • Predicts continuous emission spectra for atoms
  • Predicts the same emission spectra for all types of atoms
The possible quantum number for $$3d$$ electron are 
  • $$n=3, l=1, m_1=+1, m_s=-\dfrac 12$$
  • $$n=3, l=2, m_1=+2, m_s=-\dfrac 12$$
  • $$n=3, l=1, m_1=-1, m_s=+\dfrac 12$$
  • $$n=3, l=0, m_1=+1, m_s=-\dfrac 12$$
The radius of the first ( lowest ) orbit of the hydrogen atom is $$a_0$$. The radius of the second ( next higher ) orbit will be 
  • $$4a_0$$
  • $$6a_0$$
  • $$8a_0$$
  • $$10a_0$$
Radius of first Bohr orbit is $$r$$. What is the radius of $$2-$$Bohr orbit?
  • $$8\ r$$
  • $$2\ r$$
  • $$4\ r$$
  • $$2\ \sqrt {2r}$$
In hydrogen atom which quantity is integral multiple of $$\dfrac{h}{2\pi}$$
  • Angular momentum
  • Angular velocity
  • Angular acceleration
  • Momentum
The diagram shows the path of four $$\alpha$$- particles of the same energy being scattered by the nucleus of an atom simultaneously. Which of these are/ is not physically possible 
1819709_cdcc2e6c94db43969932fcbb8364b9e1.png
  • $$3$$ and $$4$$
  • $$2$$ and $$3$$
  • $$1$$ and $$4$$
  • $$4$$ only
Line spectrum contains information about
  • The atoms of the prism
  • The atoms of the source
  • The molecules of the source
  • The atoms as well as molecules of the source
Line spectra are due to
  • Hot solids
  • Atoms in gaseous state
  • Molecules in gaseous state
  • Liquid at low temperature
The spectrum obtained from a sodium vapour lamp is an example of
  • Absorption spectrum
  • Emission spectrum
  • Continuous spectrum
  • Band spectrum
The solar spectrum during a complete solar eclipse is
  • Continuous
  • Emission line
  • Dark line
  • Dark band
In which part of the electromagnetic spectrum the Lyman series of hydrogen is found ?
  • ultraviolet
  • infrared
  • visible
  • X-ray region
The nature of suns spectrum is
  • Continuous spectrum with absorption lines
  • Line spectrum
  • The spectrum of the helium atom
  • Band spectrum
When a hydrogen atom is raised from ground to excited state.
  • The P.E increases and K.E decreases
  • The P.E decreases and K.E increases
  • Both P.E and K.E increase
  • Both P.E and K.E decreases
In which of the following systems will the radius of the first orbit of the electron be smallest?
  • hydrogen
  • singly ionized helium
  • deuteron
  • tritium
In which of these, will radius of first orbit be minimum?
  • $$H$$ atom
  • $$^{2}_{1}H$$ atom
  • $$He^{+}$$ ion
  • $$Li^{2+}$$ ion
The allowed momenta are given by
74386_361656947959429180aa8e8aaf5b37c3.png
  • $$\dfrac{nh}{2L}$$
  • $$\dfrac{nh}{L}$$
  • $$\dfrac{nh}{2\Pi L}$$
  • $$\dfrac{nh}{4L}$$
The allowed kinetic energy of the particle is
74386_361656947959429180aa8e8aaf5b37c3.png
  • $$\dfrac{n^{2}h^{2}}{8\pi ^{2}mL^{2}}$$
  • $$\dfrac{n^{2}h^{2}}{2mL^{2}}$$
  • $$\dfrac{n^{2}h^{2}}{8mL^{2}}$$
  • $$\dfrac{n^{2}h^{2}}{32mL^{2}}$$
Assume an imaginary world where angular momentum is quantized to even multiple. The longest possible wave length emitted by hydrogen in the visible spectrum is
  • $$484 nm$$
  • $$300 nm$$
  • $$400 nm$$
  • $$350 nm$$
A particle of mass $$m$$ moves around in a circular orbit in a centro symmetric potential field u(r)$$=\dfrac{kr^{2}}{2}$$. Using Bohr’s quantization rule, the permissible energy levels are 
  • $$\sqrt{\dfrac{k}{m}}$$
  • $$n\sqrt{\dfrac{k}{m}}$$
  • $$n$$
  • $$\sqrt{\dfrac{nk}{m}}$$
Let $$\mathrm{v}_{1}$$ be the frequency of the series limit for Lyman series, $$\mathrm{v}_{2}$$ the frequency of the first line of the Lyman series and $$\mathrm{v}_{3}$$ the frequency of the series limit of Balmer series. Then which of the following relations is true?
  • $$\mathrm{v}_{1}-\mathrm{v}_{2}=\mathrm{v}_{3}$$
  • $$\mathrm{v}_{2}-\mathrm{v}_{1}=\mathrm{v}_{3}$$
  • $$\displaystyle \mathrm{v}_{3}=\frac{\mathrm{v}_{1}+\mathrm{v}_{2}}{2}$$
  • $$\mathrm{v}_{1}+\mathrm{v}_{2}=\mathrm{v}_{3}$$
The radius of hydrogen atom is 0.53 $$\mathop A\limits^0$$. The radius of $$Li^{2+}$$ is of
  • $$1.27\mathop A\limits^0 $$
  • $$0.17 \mathop A\limits^0$$
  • $$0.57 \mathop A\limits^0$$
  • $$0.99 \mathop A\limits^0$$

Whenever a hydrogen atom emits a photon in the Balmer series,
  • it may emit another photon in the Balmer series.
  • it must emit another photon in the Lyman series.
  • the second photon, it emitted, will have a wavelength of about 122 nm.
  • it may emit a second photon, but the wavelength of this photon cannot be predicted.
When $$Z$$ is doubled in a hydrogen like atom, which of the following statements are consistent with Bohr's theory?
  • Energy of a state is double
  • Radius of an orbit is doubled
  • Velocity of electrons in an orbit is doubled
  • Radius of an orbit is halved
The difference between I and II energy levels is

74386_361656947959429180aa8e8aaf5b37c3.png
  • $$ 1.5\times 10^{-18} J$$
  • $$ 3\times 10^{-18} J$$
  • $$ 6\times 10^{-18} J$$
  • $$ 12\times 10^{-18} J$$
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