Nuclei — DPP 3

20 NEET questions from Nuclei, with answers and explanations. Attempt it as a timed test to get scoring, accuracy breakdown and mistake tracking.

Attempt this test free 20 questions · 30 minutes · +80 marks
1
In ${ }_{88} \mathrm{Ra}^{226}$ nucleus, there are:
  1. A 138 protons and 88 neutrons
  2. B 138 neutrons and 88 protons
  3. C 226 protons and 88 electrons
  4. D 226 neutrons and 138 electrons
Show answer

Correct answer: B

2
The equation $4 _ { 1 } \mathrm { H } ^ { 1 } \rightarrow { } _ { 2 } \mathrm { He } ^ { 4 + + } + 2 \mathrm { e } ^ { + } + 26 \mathrm { MeV }$ represents:
  1. A γ-decay
  2. B β-decay
  3. C Fission
  4. D Fusion
Show answer

Correct answer: D

3
The mass defect for the nucleus of helium is 0.0303 a.m.u. What is the binding energy per nucleon for helium in MeV?
  1. A 28
  2. B 7
  3. C 4
  4. D 1
Show answer

Correct answer: B

4
Outside a nucleus:
  1. A Neutron is stable
  2. B Both Proton and neutron are stable
  3. C Neutron is unstable
  4. D Both neutron and proton are unstable
Show answer

Correct answer: C

5
If the mass number of an atom is A = 40 and its electron configuration is $1 \mathrm {~s} ^ { 2 } , 2 \mathrm {~s} ^ { 2 } , 2 \mathrm { p } ^ { 6 } , 3 \mathrm {~s} ^ { 2 } , 3 \mathrm { p } ^ { 6 }$, the number of neutrons and protons in its nucleus will be:
  1. A 22, 18
  2. B 18, 22
  3. C 20, 20
  4. D 18, 18
Show answer

Correct answer: A

6
Isobars are formed by:
  1. A $\alpha$-decay
  2. B β-decay
  3. C $\gamma$-decay
  4. D Cosmic decay
Show answer

Correct answer: B

7
Calculate binding energy of an alpha particle from the following data:
Mass of free proton = 1.00727 a.m.u
Mass of free neutron = 1.008665 a.m.u
Mass of helium nucleus = 4.002800 a.m.u
1 a.m.u = 931.5 Mev
  1. A 28.5 Mev
  2. B 28.3 Mev
  3. C 27.1 Mev
  4. D 28.7 Mev
Show answer

Correct answer: C

8
The energy equivalent of one atomic mass unit is
  1. A $16 \times 10 ^ { - 19 } \mathrm {~J}$
  2. B $6.02 \times 10 ^ { 23 } \mathrm {~J}$
  3. C 931 MeV
  4. D 9.31 MeV
Show answer

Correct answer: C

9
$m _ { p }$ denotes the mass of a proton and $m _ { n }$ that of a neutron. A given nucleus of binding energy BE, contains N protons and N neutrons. The mass m(N, Z) of the nucleus is given by
  1. A $m ( N , Z ) = N m _ { n } + Z m _ { p } - ( B E ) c ^ { 2 }$
  2. B $m ( N , Z ) = N m _ { n } + Z m _ { p } + ( B E ) c ^ { 2 }$
  3. C $m ( N , Z ) = N m _ { n } + Z m _ { p } - B E / c ^ { 2 }$
  4. D $m ( N , Z ) = N m _ { n } + Z m _ { p } + B E / c ^ { 2 }$
Show answer

Correct answer: C

10
In the reaction ${ } _ { 1 } ^ { 2 } \mathrm { H } + { } _ { 1 } ^ { 3 } \mathrm { H } \rightarrow { } _ { 2 } ^ { 4 } \mathrm { He } + { } _ { 0 } ^ { 1 } n$, if the binding energies of ${ } _ { 1 } ^ { 2 } \mathrm { H } , { } _ { 1 } ^ { 3 } \mathrm { H }$ and ${ } _ { 2 } ^ { 4 } \mathrm { He }$ are respectively a , b, and c (in MeV), then the energy (in MeV) released in this reaction is
  1. A c + a - b
  2. B c - a - b
  3. C $\ddot { u } + +$
  4. D a + b - c
Show answer

Correct answer: B

11
Energy of 21 g uranium is equal to:
  1. A $9.0 \times 10 ^ { 13 } \mathrm {~J}$
  2. B $21 \times 10 ^ { - 9 } \mathrm {~J}$
  3. C $189 \times 10 ^ { 13 } \mathrm {~J}$
  4. D $1.9 \times 10 ^ { 12 } \mathrm {~J}$
Show answer

Correct answer: C

12
For effective nuclear forces, the distance should be:
  1. A $1 \AA$
  2. B 10 pm
  3. C 0.1 pm
  4. D 1 fm
Show answer

Correct answer: D

13
In which radioactive disintegration neutron dissociates into proton and electron?
  1. A $\mathrm { He } ^ { + 1 }$ emission
  2. B $\beta$-emision
  3. C $\gamma$-emission
  4. D Positron emission
Show answer

Correct answer: B

14
A radioactive nucleus undergoes a series of decays according to the sequence $\mathrm { A } \xrightarrow { \beta } \mathrm { A } _ { 1 } \xrightarrow { \alpha } \mathrm {~A} _ { 2 } \xrightarrow { \alpha } \mathrm {~A} _ { 3 }$. If the mass number and atomic number of $\mathrm { A } _ { 3 }$ are 172 and 69 respectively, then the mass number and atomic number of A is
  1. A 56, 23
  2. B 180, 72
  3. C 120, 52
  4. D 84, 38
Show answer

Correct answer: B

15
Consider α and β particles and γ-rays each having an energy of 0.5 MeV. In the increasing order of penetrating power, the radiation is respectively:
  1. A $\alpha , \beta , \gamma$
  2. B $\alpha , \gamma , \beta$
  3. C $\beta , \gamma , \alpha$
  4. D $\gamma , \beta , \alpha$
Show answer

Correct answer: A

16
Energy released in the fission of a single ${ } _ { 92 } \mathrm { U } ^ { 235 }$ nucleus is 200 MeV. The fission rate of $\mathrm { a } _ { 92 } \mathrm { U } ^ { 235 }$ fueled reactor operating at a power level of 5 W is:
  1. A $1.56 \times 10 ^ { 10 } \mathrm {~s} ^ { - 1 }$
  2. B $1.56 \times 10 ^ { 11 } \mathrm {~s} ^ { - 1 }$
  3. C $1.56 \times 10 ^ { 16 } \mathrm {~s} ^ { - 1 }$
  4. D $1.56 \times 10 ^ { 17 } \mathrm {~s} ^ { - 1 }$
Show answer

Correct answer: B

17
Pick out the incorrect statement from the following:
  1. A $\beta$-emission from the nucleus is always accompanied with a neutrino
  2. B The energy of the $\alpha$-particle emitted from a given nucleus is always constant
  3. C $\gamma$-ray emission makes the nucleus more stable
  4. D Nuclear force is charge - independent
Show answer

Correct answer: A

18
The isotope ${ } _ { 92 } ^ { 238 } \mathrm { U }$ decays successively to form ${ } _ { 90 } ^ { 234 } \mathrm { Th } , { } _ { 91 } ^ { 234 } \mathrm {~Pa}$, ${ } _ { 92 } ^ { 234 } \mathrm { U } , { } _ { 90 } ^ { 230 } \mathrm { Th }$ and ${ } _ { 88 } ^ { 226 } \mathrm { Ra }$. The radiations emitted in these five steps are
  1. A $\alpha , \alpha , \alpha , \beta , \beta$
  2. B $\alpha , \alpha , \beta , \beta , \alpha$
  3. C $\alpha , \beta , \beta , \alpha , \alpha$
  4. D $\beta , \beta , \alpha , \alpha , \alpha$
Show answer

Correct answer: C

19
The nuclide which disintegrates by emitting a $\beta ^ { - }$particle to form ${ } _ { 7 } ^ { 14 } \mathrm {~N}$ contains
  1. A 8 neutrons
  2. B 10 neutrons
  3. C 7 neutrons
  4. D 6 neutrons
Show answer

Correct answer: A

20
If the energy released in the fission of one nucleus is 200 MeV, then the number of nuclei required per second in a power plant of 16 kW will be:
  1. A $0.5 \times 10 ^ { 14 }$
  2. B $0.5 \times 10 ^ { 12 }$
  3. C $5 \times 10 ^ { 12 }$
  4. D $5 \times 10 ^ { 14 }$
Show answer & explanation

Correct answer: D

Energy release is the fission of one nucleus = 200 MeV
$=200 \times 1.6 \times 10^{-19} \times 10^{6} \mathrm{~J}=3.2 \times 10^{-11} \mathrm{~J}$
P = 16 kW = 16 × 10$^{3}$ watt
Now, number of nuclei required per second.
$\mathrm{n}=\frac{\mathrm{P}}{\mathrm{E}}=\frac{16 \times 10^{3}}{3.2 \times 10^{-11}}=5 \times 10^{14}$
Therefore, option (D) is the correct answer.

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