Nuclei — DPP 1

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
A radioactive nucleus undergoes a series of decays according to the following scheme
$\mathrm{A} \xrightarrow{\alpha} \mathrm{A}_{1} \xrightarrow{\beta^{-}} \mathrm{A}_{2} \xrightarrow{\alpha} \mathrm{~A}_{3} \xrightarrow{\gamma} \mathrm{~A}_{4}$
If the mass number and atomic number of A are 180 and 72 respectively, what are these numbers for $\mathrm { A } _ { 4 }$ ?
  1. A A = 176 and Z = 69
  2. B A = 172 and Z = 69
  3. C A = 170 and Z = 69
  4. D A = 175 and Z = 69
Show answer

Correct answer: B

2
Find the density of ${ } _ { 6 } ^ { 12 } \mathrm { C }$ (Atomic mass $= 12 \mathrm { amu }$; $\mathrm { R } _ { \mathrm { o } } = 1.2 \times 10 ^ { - 15 } \mathrm {~m}$ )
  1. A $2.4 \times 10 ^ { 17 } \mathrm {~kg} \mathrm {~m} ^ { - 3 }$
  2. B $3.4 \times 10 ^ { 17 } \mathrm {~kg} \mathrm {~m} ^ { - 3 }$
  3. C $1.1 \times 10 ^ { 17 } \mathrm {~kg} \mathrm {~m} ^ { - 3 }$
  4. D $4.4 \times 10 ^ { 17 } \mathrm {~kg} \mathrm {~m} ^ { - 3 }$
Show answer

Correct answer: A

3
Two nuclei which are not identical but have the same number of nucleons represent
  1. A Isotones
  2. B Isobars
  3. C Isotopes
  4. D Can't predict
Show answer

Correct answer: B

4
In a nuclear fusion reaction, if the energy is released then
  1. A $B E _ { \text {products } } = B E _ { \text {reactants } }$
  2. B $B E _ { \text {reactants } } > B E _ { \text {products } }$
  3. C $B E _ { \text {products } } > B E _ { \text {reactants } }$
  4. D Mass of product > Mass of reactant
Show answer

Correct answer: C

5
${ } _ { a } \mathrm { X } ^ { b } \xrightarrow { - \beta ^ { 0 } } \xrightarrow { \alpha } { } _ { c } \mathrm { Y } ^ { 215 } \xrightarrow { - \beta ^ { 0 } } { } _ { 110 } \mathrm { Y } ^ { d }$ Find $\mathrm { a } , \mathrm { b } , \mathrm { c }$ and d .
  1. A a = 110, b = 218, c = 109, d = 216
  2. B a = 110, b = 219, c = 108, d = 218
  3. C a = 110, b = 219, c = 109, d = 215
  4. D a = 109, b = 219, c = 109, d = 220
Show answer

Correct answer: C

6
Boron rods are used in nuclear reactors because
  1. A boron can absorb neutrons
  2. B strength is given to the plant
  3. C boron speeds up neutrons
  4. D slows down the neutrons
Show answer

Correct answer: A

7
In nuclear reactions, we have the conservation of
  1. A Mass only
  2. B Energy only
  3. C Momentum only
  4. D Charge, total energy and momentum
Show answer

Correct answer: D

8
When two nuclei of mass X and Y respectively fuse to form a nucleus of mass m along with the liberation of some energy, then
  1. A X + Y > m
  2. B X - Y = m
  3. C X + Y = m
  4. D X + Y < m
Show answer

Correct answer: A

9
Number of protons and neutrons in ${ } _ { 90 } \mathrm { Th } ^ { 234 }$ respectively are:
  1. A 90, 234
  2. B 144, 90
  3. C 90, 144
  4. D 234, 90
Show answer & explanation

Correct answer: C

P = 90 , n = 234 – 90 = 144
Therefore, option (C) is the correct answer.
10
${ } _ { 92 } \mathrm { U } ^ { 238 } \xrightarrow { \alpha } \xrightarrow { + \beta ^ { 0 } } { } _ { \mathrm { a } } \mathrm { X } ^ { \mathrm { b } }$, find a and b.
  1. A a = 89, b = 234
  2. B a = 79, b = 235
  3. C a = 69, b = 233
  4. D a = 90, b = 240
Show answer

Correct answer: A

11
Isotopes are atoms having;
  1. A Same number of protons but different number of neutrons.
  2. B Same number of neutrons but different number of protons.
  3. C Same number of protons and neutrons.
  4. D different number of protons and neutrons.
Show answer

Correct answer: A

12
The nuclear radius as compared to the atomic radius is of the order
  1. A $10 ^ { - 3 }$
  2. B $10 ^ { - 5 }$
  3. C $10 ^ { - 7 }$
  4. D $10 ^ { - 9 }$
Show answer

Correct answer: B

13
The nuclei ${ } _ { 6 } A ^ { 13 }$ and ${ } _ { 7 } B ^ { 14 }$ can be described as
  1. A Isotones
  2. B Isobars
  3. C Isotopes of carbon
  4. D Isotopes of nitrogen
Show answer

Correct answer: A

14
The ratio of radii of 2 nuclei with mass number 1 and 64 respectively is:
  1. A 1/64
  2. B 1/4
  3. C 1/8
  4. D 1/2
Show answer & explanation

Correct answer: B

$\frac{R_{1}}{R_{2}}=\left[\frac{A_{1}}{A_{2}}\right]^{1 / 3}=\left[\frac{1}{64}\right]^{1 / 3}=\frac{1}{4}$
Therefore, option (B) is the correct answer.
15
Radius of ${ } _ { 2 } ^ { 4 } \mathrm { He }$ nucleus is 3 Fermi. The radius of ${ } _ { 47 } ^ { 108 } \mathrm { Ag }$ nucleus will be;
  1. A 5 Fermi
  2. B 6 Fermi
  3. C 9 Fermi
  4. D 8 Fermi
Show answer

Correct answer: C

16
Ratio of nuclear radii of ${ } ^ { 135 } \mathrm { Cs }$ to ${ } ^ { 40 } \mathrm { Ca }$ is
  1. A 1.40
  2. B 1.50
  3. C 2.750
  4. D 3.375
Show answer

Correct answer: B

17
Two nuclei have their mass numbers in ratio 1 : 3. What is the ratio of nuclear densities?
  1. A 1 : 2
  2. B 1 : 3
  3. C 1 : 4
  4. D 1 : 1
Show answer

Correct answer: D

18
Which of the following pairs of particles cannot exert nuclear force on each other?
  1. A proton and proton
  2. B neutron and neutron
  3. C proton and neutron
  4. D proton and electron
Show answer

Correct answer: D

19
If $F _ { p p } , F _ { p n }$ and $F _ { n n }$ are the magnitudes of nuclear force between proton-proton, proton-neutron and neutron-neutron respectively, then
  1. A $F _ { p p } = F _ { p n } = F _ { n n }$
  2. B $F _ { p n } > F _ { p p } > F _ { n n }$
  3. C $F _ { p p } > F _ { p n } > F _ { n n }$
  4. D $F _ { p p } < F _ { p n } < F _ { n n }$
Show answer

Correct answer: A

20
Calculate the binding energy (in approx.) of ${ } _ { 17 } \mathrm { Cl } ^ { 35 }$ if mass of ${ } _ { 17 } \mathrm { Cl } ^ { 35 }$ nucleus is 34.98 amu , mass of neutron is 1.008665 amu and mass of proton is 1.007277 amu.
  1. A 260 MeV
  2. B 279 MeV
  3. C 240 MeV
  4. D 289 MeV
Show answer

Correct answer: B

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