Physics - Nuclei - Quiz-5

A radioactivity nuclide can decay simultaneously by two different processes that have decay constants $λ_{1}$ and $λ_{2}$ . The effective decay constant of the nuclide is $λ .$ Then-

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$λ = λ_{1} + λ_{2}$
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$λ = \frac{1}{2} (λ_{1} + λ_{2})$
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$\frac{1}{λ} = \frac{1}{λ_{1}} + \frac{1}{λ_{2}}$
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$λ = \sqrt{λ_{1} v_{2}}$

Which of the following is deflected by electric field

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X-rays
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Gamma rays
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Neutrons
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α-particles

The half-life of a radioactive substance is 30 minutes. The time (in minute) taken between 40% decay and 85% decay of the same radioactive substance is

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15
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30
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45
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60

If the radius of the ₁₃Al²⁷ nucleus is taken to R_Al then the radius of ₅₃Te¹²⁵ nucleus is nearly

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(53/13)^1/3 R_Al
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5/3 R_Al
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3/5 R_Al
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(13/53)^1/3R_Al

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then,

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the helium nucleus has more kinetic energy than the thorium nucleus
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the helium nucleus has less momentum than the thorium nucleus
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the helium nucleus has more momentum than the thorium nucleus
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the helium nucleus has less kinetic energy than the thorium nucleus

The binding energy per nucleon of ${}_{3}^{7}{Li}$ and ${}_{2}^{4}{He}$ nuclei are 5.60meV and 7.06meV, respectively.
In the nuclear reaction ${}_{3}^{7}{Li} + {}_{1}^{1}H \to {}_{2}^{4}{He} + {}_{2}^{4}{He} + Q$ , the value of energy Q released is -
(a)19.6MeV
(b)-2.4MeV
(c)8.4MeV
(d)17.3MeV

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1
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2
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3
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4

A radioisotope X with a half-life 1.4x10⁹ yr decays into Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 1:7. The age of the rock is
(1)1.96x10⁹ yr

(2)3.92x10⁹ yr

(3)4.20x10⁹ yr

(4)8.40x10⁹yr

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1
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2
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3
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4

A mixture consists of two radioactive materials $A_{1}$ and $A_{2}$ with half lives of 20 s and 10 s respectively.Initially the mixture has 40g of $A_{1}$ and 160g of $A_{2}$ . The amount of the two in the mixture will become equal after

(a)60 s (b)80 s

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1
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2
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3
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4

The half life of a radioactive nucleus is 50 days. The time interval $(t_{2} - t_{1})$ between the time $t_{2}$ when $\frac{2}{3}$ of it has decayed and the time $t_{1}$ when $\frac{1}{3}$ of it had decayed is

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30 days
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50 days
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60 days
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15 days

Fusion reaction takes place at high temperature because

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atoms get ionised at high temperature
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kinetic energy is high enough to overcome the Coulomb repulsion between nuclei
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molecules break up at high temperature
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nuclei break up at high temperature

Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t=0, the number of P species are $4 N_{0}$ and that of Q is and that of Q are $N_{0} .$ Half-life of P(for conversion to R) is 1 min whereas that of Q is 2 min. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be:

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$3 N_{0}$
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$\frac{9 N_{0}}{2}$
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$\frac{5 N_{0}}{2}$
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$2 N_{0}$

The mass of a ${}_{3}^{7}L i$ nucleus is 0.042u less than the sum of the masses of its nucleons.The binding energy per nucleon of ${}_{3}^{7}L i$ nucleus is nearly

(a) 46 MeV (b) 5.6 MeV

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1
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2
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4

The activity of a radioactive sample is measured as $N_{0}$ counts per minute at t=0 and $N_{0} / e$ counts per minute at t=5 min.The time (in minute) at which the activity reduces to half its value is

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$\log_{e} 2 / 5$
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$\frac{5}{\log_{e} 2}$
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$5 \log_{10} 2$
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$5 \log_{e} 2$

The decay constant of a radio isotope is $λ .$ If $A_{1}$ and $A_{2}$ are its activities at times $t_{1}$ and $t_{2}$ respectively, the number of nuclei which have decayed during the time $(t_{1} - t_{2}) is:$

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$A_{1} t_{1} - A_{2} t_{2}$
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$A_{1} - A_{2}$
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$\frac{(A_{1} - A_{2})}{λ}$
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$λ (A_{1} - A_{2})$

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an

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isobar of parent
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isomer of parent
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isotone of parent
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isotope of parent

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

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1:3
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3:1
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${(3)}^{1 / 3} : 1$
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1:1

The size of an atom is of the order of
(a) $10^{- 8}$ m (b) $10^{- 10} m$
(c) $10^{- 12} m$ (d) $10^{- 14} m$

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1
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2
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3
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The order of the size of nucleus and Bohr radius of an atom respectively are

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$10^{- 14} m, 10^{- 10} m$
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$10^{- 10} m, 10^{- 8} m$
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$10^{- 20} m, 10^{- 16} m$
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$10^{- 8} m, 10^{- 6} m$

Which of the following particles are constituents of the nucleus

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Protons and electrons
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Protons and neutrons
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Neutrons and electrons
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Neutrons and positrons

Nuclear binding energy is equivalent to

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Mass of proton
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Mass of neutron
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Mass of nucleus
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Mass defect of nucleus

The mass defect given in a.m.u. is

(2) – 0.0012

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– 0.0024
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(3) 0.0012
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If the binding energy of the deutrium is 2.23 MeV.
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0.0024

Which of the following has the mass closest in value to that of the positron

(1) Proton

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(1 mu = 931 MeV)
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(2) Electron
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(3) Photon
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(4) Neutrino

Size of nucleus is of the order of

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$10^{- 10} m$
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$10^{- 15} m$
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$10^{- 12} m$
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$10^{- 19} m$

For effective nuclear forces, the distance should be

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$10^{- 10} m$
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$10^{- 13} m$
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$10^{- 15} m$
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$10^{- 20} m$

The masses of neutron and proton are 1.0087 a.m.u. and 1.0073 a.m.u. respectively. If the neutrons and protons combine to form a helium nucleus (alpha particle) of mass 4.0015 a.m.u. The binding energy of the helium nucleus will be (1 a.m.u.= 931 MeV) :

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28.4 MeV
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20.8 MeV
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27.3 MeV
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14.2 MeV

Atomic power station at Tarapore has a generating capacity of 200 MW. The energy generated in a day by this station is

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200 MW
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200 J
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$4800 \times 10^{6} J$
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$1728 \times 10^{10}$ J

The binding energy of deuteron ${}_{1}^{2}H$ is 1.112 MeV per nucleon and an $α$ -particle ${}_{2}^{4}{He}$ has a binding energy of 7.047 MeV per nucleon. Then in the fusion reaction ${}_{1}^{2}H + {}_{1}^{2}H \to {}_{2}^{4}{He} + Q$ , the energy Q released is

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1 MeV
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11.9 MeV
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23.8 MeV
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931 MeV

Binding energy of a nucleus is:

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Energy given to its nucleus during its formation
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Total mass of nucleus converted to energy units
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Loss of energy from the nucleus during its formation
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Total K.E. and P.E. of the nucleons in the nucleus

Which of the following pairs is an isobar

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${}_{1}H_{1}$ and ${}_{1}H_{2}$
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${}_{1}H_{2}$ and ${}_{1}H_{3}$
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${}_{6}C_{12}$ and ${}_{6}C_{13}$
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${}_{15}P_{30}$ and ${}_{14}{Si}_{30}$

Equivalent energy of mass equal to 1 a.m.u. is

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931 KeV
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931 eV
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931 MeV
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9.31 MeV

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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