NEET Physics Chapter Wise Mock Test – Modern Physics
Question 1.
The de-Broglie wavelength associated with a proton moving with a velocity, equal to 1/20 th of the velocity of light
(a) 2.834×10-14 m
(b) 1.5×10-7m
(c) 1.5×107 m
(d) 2.634×1014 m
Question 2.
An electron has been accelerated from rest through a potential difference of 100V, its de-Broglie wavelength is
(a) 225Å
(b) 1.225Å
(c) 225m
(d) 1.225cm
Question 3.
The experiments of Frank and Hertz showed that
(a) an atom has energy states having a continuous distribution
(b) nothing can be send a bond energy states of atom
(c) at atom has energy states, having discrete values
(d) atom is an indivisible particle
Question 4.
A photon and an electron have same energy, the ratio of their wavelengths is
Question 5.
If the wavelength of incident light changes from 400nm to 300nm, the stopping potential for photoelectrons emitted from a surface becomes approximately
(a) 1.0V greater
(b) 1.0V smaller
(c) 0.5V greater
(d) 0.5V smaller
Question 6.
The photosensitive surface is receiving light of wavelength 5000Å at the rate of 10-8 Js-1. The number of photons received per second, is
(a) 2.5 x 1010
(b) 2.5 x 1011
(c) 2.5 x 1012
(d) 2.5 x 109
Question 7.
The wavelength of quantum of radiant energy emitted, if an electron transmitted into radiation and converted into one quantum, is
(a) 0.0242Å
(b) 2.42Å
(c) 532Å
(d) 0.532Å
Question 8.
The electric potential at the surface of an atomic nucleus (Z=50) of radius 9.0 x 10-13 cm, is
(a) 9x 105 V
(b) 8 x 106 V
(c) 80V
(d) 9V
Question 9.
Kα wavelength emitted by an atom of atomic number Z=11 is λ. Find the atomic number for an atom that emits Kα radiation with wavelength 4λ, is
(a) Z=6
(b) Z=4
(c) Z=11
(d) Z=44
Question 10.
The ratio of minimum wavelengths of Lyman and Balmer series will be
(a) 1.25
(b) 0.25
(c) 5
(d) 10
Question 11.
What will be the amount of energy absorbed when an electron jumps from first orbit to second orbits, if the value of energy in nth orbit of H-atom is expressed as (En=-13.6/n2 eV)
(a) -3.4eV
(b) -66eV
(c) -8.1eV
(d) -10.2eV
Question 12.
An electron changes its position from orbit n=2 to the orbit n=4 of an atom. The wavelength of the emitted radiations is (R = Rydberg’s constant)
(a) 16/R
(b) 16/3R
(c) 16/5R
(d) 16/7R
Question 13.
Imagine an atom made of a proton and a hypothetical particle of double the mass of the electron but having same charge as the electron. Apply Bohr atom model and consider all possible transitions of the hypothetical particle to the first excited level. The longest wavelength photon that will be emitted has wavelength λ equal to
(a) 9/5R
(b) 36/5R
(c) 18/5R
(d) 4/R
Question 14.
Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in 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
(a) 2
(b) 3
(c) 4
(d) 1
Question 15.
In Bohr’s model the atomic radius of the first orbit is r0, the radius of the third orbit will be
(a) 9r0
(b) 3r0
(c) r0
(d) r0/3
Question 16.
Taking Rydberg’s constant =1.097 x107 m first and second wavelength of Balmer series in hydrogen spectrum, is
(a) 2000Å, 3000Å
(b) 1575Å, 2960Å
(c) 6529Å, 4280Å
(d) 6562Å, 4863Å
Question 17.
Which of the following lines of the H-atom spectrum belengs to Balmer series?
(a) 1025Å
(b) 12184Å
(c) 4861Å
(d) 18751Å
Question 18.
The density of uranium is of the Order of
(a) 1020 kgm-3
(b) 1017 kgm-3
(c) 1014 kgm-3
(d) 1011 kgm-3
Question 19.
Two radioactive materials A and B have decay constants 10λ and λ, respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of A to that of B will be 1/e after a time.
(a) 1/10λ
(b) 1/11λ
(c) 11/10λ
(d) 1/9λ
Question 20.
Question 21.
If R is the radius and A is the mass number, then log R versus log A graph will be
(a) a straight line
(b) a parabola
(c) an ellipse
(d) a hyperbola
Question 22.
Question 23.
A radioactive substance has a half-life of four months. Three-fourth of the substance will decay in
(a) 3 months
(b) 4 months
(c) 8 months
(d) 12 months
Question 24.
C14 has half-life 5700 yr. At the end of 11400 yr, actual amount left is
(a) 0.5 of original amount
(b) 0.25 of original amount
(c) 0.125 of original amount
(d) 0.0625 of original amount
Question 25.
208Ra has half-life 120 days. The amount of 208Ra, if the activity level is one mCi
(a) 0.184 μg
(b) 0.184 mg
(c) 0.134 μg
(d) 0.314 mg
Question 26.
The counting rate observed from a radioactive source at t=0s was 1600 counts/s-1, and at t = 8s it was 100 count/s-1. The counting rate observed at t=6s was
(a) 400
(b) 300
(c) 200
(d) 150
Question 27.
Mean life of a radioactive sample is 100s. Then, its half-life (in minute) is
(a) 0.693
(b) 1
(c) 10-4
(d) 1.155
Question 28.
If parent decays to daughter nucleus with a rate r and daughter nucleus has average life τ and number of nuclei of daughter nucleus at any instant is N, then for radioactive equilibrium to be achieved, we have
(a) r=Nτ
(b) r=τN
(c) rτ=N
(d) τ=r
Question 29.
In a specific case, angular momentum is an even integral multiple of h/2π. The longest possible wavelength emitted by hydrogen in visible region in such a world, according to Bohr’s model is
(a) 273 nm
(b) 474 nm
(c) 523 nm
(d) zero
Question 30.
If the binding energies of a deuteron and an α-particle are 1.125 MeV and 7.2 MeV, respectively. Then, the more stable of the two is
(a) deuteron
(b) α-particle
(c) Both (a) and (b)
(d) sometimes deuteron and sometimes alpha particle
Question 31.
The nuclei of which one of the following pairs of nuclei are isotones?
(a) 34Se74, 31Ga71
(b) 42Mo92, 40Zr92
(c) 38Sr84, 38Sr86
(d) 20Ca40, 16S32
Question 32.
In the nuclear reaction,
the atomic mass and atomic number of P are, respectively
(a) 170,69
(b) 172,69
(c) 172, 70
(d) 170, 70
Question 33.
A nuclei X with mass number A and charge number Z, disintegrates into one α-particle and one β-particle. The resulting nuclide R has atomic mass and atomic number, equal to
(a) (A – Z) and (Z – 1)
(b) (A – Z) and (Z – 2)
(c) (A – 4) and (A – 2)
(d) (A – 4) and (Z -1)
Question 34.
In a nuclear reaction
What does X stand for?
(a) An electron
(b) A proton
(c) A neutron
(d) A neutrino
Question 35.
The particle A is converted into C via following reaction,
Then,
(a) A and C are isobars
(b) A and C are isotopes
(c) A and B are isobars
(d) A and B are isotopes
Question 36.
A nucleus with mass number 220 initially emits α-particle. If the Q value of the reaction is 5.5 MeV. Then, the kinetic energy of the α-particle is
(a) 4.4 MeV
(b) 5.4 MeV
(c) 5.6 eV
(d) 6.5 eV
Direction (Q.Nos. 37-42): These questions consist of two statements, each linked as Assertion and Reason. While answering of these questions, you are required to choose any one of the following.
(a) If both Assertion and Reason are true and Reason is the correct explanation of the Assertion
(b) If both Assertion and Reason are true but Reason is not correct explanation of the Assertion
(c) If Assertion is true but Reason is false
(d) If Assertion is false but Reason is true
Question 37.
Assertion (A): If wavelength of incident photons is halved, then maximum kinetic energy of photoelectron will become two times.
Reason (R): Energy of photon ∝ 1/λ
Question 38.
Assertion (A): Second orbit circumference of hydrogen atom is two times the de-Broglie wavelength of electrons in that orbit.
Reason (R): de-Broglie wavelength of electron in ground state is minimum.
Question 39.
Assertion (A): Energy E1 is required to remove first electron from helium atom and energy E2 is to required to remove the second electron. Then, E1<E2
Reason (R): Ionisation energy of single electron of He+,is 54.4 eV.
Question 40.
Assertion (A): If high pressure is applied on a radioactive substance, rate of radioactivity will increase.
Reason (R): Radioactivity is a nuclear process.
Question 41.
Assertion (A): At time t=0, activity of a radioactive substance is 10 units. At t=1s, it remains 90 units. Then, at t=2 s it should remain 80 units.
Reason (R): In equal interval of time, percentage change is same in a radioactive substance.
Question 42.
Assertion (A): If light continuously falls on a metal surface, then emission of electrons will stop after some time.
Reason (R): We cannot extract all the electrons of a metal.
Question 43.
The energy spectrum of β-particles number N(E) as a function of β energy E emitted from a radioactive source, is
Question 44.
If a star can convert all the He nuclei completely into oxygen nuclei, the energy released per oxygen nucleus is [Mass of He nucleus is 4.0026 amu and mass of oxygen nucleus is 15.9994 amu]
(a) 7.6 MeV
(b) 56.12 MeV
(c) 10.24 MeV
(d) 23.9 MeV
Question 45.
Answers:
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