The nuclear radius of a nucleus with nucleon number 16 is $3{\rm{ }} \times {\rm{ }}10{\;^{ - 15}}$ metre. Then the nuclear radius of a nucleus with nucleon number 128 is

$6{\rm{ }} \times {\rm{ }}10{\;^{ - 15}}m$

$3{\rm{ }} \times {\rm{ }}10{\;^{ - 15}}m$

$1.5{\rm{ }} \times {\rm{ }}10{\;^{ - 15}}m$

$4.5 \times {\rm{ }}10{\;^{ - 15}}m$

${{\bf{F}}_{pe}}$ represents electrical force on proton due to electron and ${{\bf{F}}_{ep}}$ on electron due to proton in a hydrogen atom.Similarly ${{\bf{F}}_{pe}}$ represents the gravitational force on proton due to electron and ${{\bf{F}}_{ep}}$ the corresponding force on electron due to proton. Which of the following is not true?

${{\bf{F}}_{Pe}} + {\bf{F'}}{\,_{Pe}} = 0$

${{\bf{F}}_{Pe}} + {{\bf{F}}_{ep}} = 0$

${\bf{F'}}{\,_{Pe}} + {\bf{F'}}{\,_{ep}} = 0$

${{\bf{F}}_{Pe}} + {\bf{F'}}{\,_{\,Pe}} + {{\bf{F}}_{ep}} + {\bf{F'}}{\,_{ep}} = 0$

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NEET • PHYSICS • NUCLEI

Nuclei practice · Mixed difficulty

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Showing 1-30 of 210 questions

1 Medium

1 of 210

Application +4 | -1

The ratio of the nuclear radii of elements with mass numbers

\mathrm{216}

and

\mathrm{125}

View answer and explanation

Correct option: C

\mathrm{6:5}

Option C (6:5) is correct because the nuclear radius is proportional to the cube root of the mass number.

2 Easy

2 of 210

Application +4 | -1

In a hypothetical fission reaction

{ }_{92} X^{236} \rightarrow{ }_{56} Y^{141}+{ }_{36} Z^{92}+3 R

The identity of emitted particles

({R})

is:

View answer and explanation

Correct option: C

Neutron

Option C (Neutron) is correct because in nuclear fission reactions, neutrons are often released as products. Checking mass and charge balance confirms this.

3 Medium

3 of 210

Application +4 | -1

The radius of the nucleus of the atom with A=216 is (take

{R_0}\; = \mathrm{ }1.3fm

)

View answer and explanation

Correct option: B

7.8 fm

Option B (7.8 fm) is correct because it is calculated using the formula for nuclear radius,

R = R_0 A^{1/3}

, where A is the mass number and

R_0 = 1.3 fm

4 Medium

4 of 210

Understanding +4 | -1

The correct sequence of the increasing wavelength of the given radiation sources is

View answer and explanation

Correct option: B

Radioactive source, X-ray tube, sodium vapour lamp, crystal oscillator

Option B is correct because it presents the electromagnetic spectrum in the correct order of increasing wavelength, from radioactive sources (shortest wavelength) to crystal oscillators (longest wavelength).

5 Easy

5 of 210

Application +4 | -1

Which of the following nuclear fragments corresponding to nuclear fission between neutron

\left({ }_0^1 \mathrm{n}\right)

and uranium isotope

\left({ }_{92}^{235} \mathrm{U}\right)

is correct:

View answer and explanation

Correct option: D

{ }_{56}^{144} \mathrm{Ba}+{ }_{36}^{89} \mathrm{Kr}+3_0^1 \mathrm{n}

Option D is correct because it accurately represents a possible fission reaction of uranium-235 with a neutron, conserving both mass number and atomic number.

6 Medium

6 of 210

Remembering +4 | -1

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

1\,\,a.m.u = 931\,\,MeV

View answer and explanation

Correct option: B

Electron

Option B is correct because a positron is the antiparticle of an electron, and therefore has the same mass as an electron.

7 Medium

7 of 210

Understanding +4 | -1

The binding energy of nucleus is a measure of its

View answer and explanation

Correct option: D

Stability

Option D (Stability) is correct because the binding energy of a nucleus is a direct measure of how stable the nucleus is.

8 Medium

8 of 210

Analyzing +4 | -1

10 gm of a radioactive element is kept in a container. The element is

\beta

-active. Then after one half-life:

(molar mass of the substance is 100 gm, Avogadro's number

=6 \times 10^{23}

per mole)

View answer and explanation

Correct option: C

If all

\beta

particles leave the container then the charge of the substance left is 4800 C

Option C is correct because after one half-life, half the radioactive material decays, and if all beta particles leave, the remaining substance will have a positive charge due to the loss of negative beta particles.

9 Medium

9 of 210

Remembering +4 | -1

Which shows radioactivity?

View answer and explanation

Correct option: C

Tritium

Option C (Tritium) is correct because Tritium, being an isotope of hydrogen with two neutrons, is radioactive.

10 Medium

10 of 210

Remembering +4 | -1

The density of uranium is of the order of

View answer and explanation

Correct option: A

{10^{20}}\,\,\mathrm{kg}{\mathrm{m}^{ - 3}}

The correct answer is not provided in the options. The density of nuclear matter is approximately

{10^{17}}\,\mathrm{kg}{\mathrm{m}^{ - 3}}

11 Medium

11 of 210

Application +4 | -1

Determine the number of nuclei that will be decayed upto one average life of radioactive material? (

{N_0}

: Initial number of nuclei)

View answer and explanation

Correct option: B

{N_0}\left( {1 - \frac{1}{e}} \right)

Option B is correct because the number of nuclei decayed up to one average life is given by the formula

N_0(1 - e^{-t/\tau})

, where

\tau

is the average life.

12 Medium

12 of 210

Remembering +4 | -1

The phenomena in which proton flips is

View answer and explanation

Correct option: A

Nuclear magnetic resonance

Option A (Nuclear magnetic resonance) is correct because it is the phenomenon where proton flips occur due to the absorption of radiofrequency radiation.

13 Medium

13 of 210

Understanding +4 | -1

Cadmium rods are used in a nuclear reactor for

View answer and explanation

Correct option: C

Absorbing neutrons

Option C (Absorbing neutrons) is correct because cadmium rods are used in nuclear reactors to absorb neutrons, thereby controlling the chain reaction and regulating the power level.

14 Hard

14 of 210

Application +4 | -1

The explosive in a hydrogen bomb is a mixture of

{ }_1 {H}^2,{ }_1 {H}^3

and

{ }_3 {Li}^6

in some condensed form. The chain reaction is given by

\begin{aligned} & { }_3 {Li}^6+{ }_0 {n}^1 \longrightarrow{ }_2 {He}^4+{ }_1 {H}^3 \\ & { }_1 {H}^2+{ }_1 {H}^3 \longrightarrow{ }_2 {He}^4+{ }_0 {n}^1 \end{aligned}

During the explosion the energy released is approximately
[Given :

{M}({Li})=6.01690\, {amu}, {M}\left({ }_1 {H}^2\right)=2.01471\, {amu}

{M}\left({ }_2 {He}^4\right)=4.00388 \,{amu}

, and

1\, {amu}=931.5 \,{MeV}

]

View answer and explanation

Correct option: A

22.22 \,{MeV}

Option A (

22.22 \,{MeV}

) is correct because it is the approximate energy released during the fusion reactions, calculated from the mass defect.

15 Easy

15 of 210

Application +4 | -1

{ }_{82}^{290} X \xrightarrow{\alpha} Y \xrightarrow{e^{+}} Z \xrightarrow{\beta^{-}} P \xrightarrow{e^{-}} Q

In the nuclear emission stated above, the mass number and atomic number of the product

Q

respectively, are

View answer and explanation

Correct option: C

286,81

Option C is correct because after one alpha emission, one positron emission, and one beta-minus emission, and one electron capture, the mass number decreases by 4 and the atomic number decreases by 1 overall.

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16 Medium

16 of 210

Understanding +4 | -1

For a nucleus to be stable, the correct relation between neutron number

N

and proton number

Z

View answer and explanation

Correct option: D

N \ge Z

Option D (

N \ge Z

) is correct because for stable nuclei, the number of neutrons is generally greater than or equal to the number of protons, especially for heavier nuclei.

17 Easy

17 of 210

Understanding +4 | -1

Assertion: For an element generally

N \geq Z(N=

number of neutrons,

Z=

atomic number)
Reason: Neutrons always experience attractive nuclear force.

View answer and explanation

Correct option: B

If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion

Option B (If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion) is correct because both statements are factually correct, but the neutron's attractive force isn't the primary reason for the N >= Z trend.

18 Medium

18 of 210

Application +4 | -1

The nuclear radius of a nucleus with nucleon number 16 is

3\mathrm{ } \times \mathrm{ }10{\;^{ - 15}}

metre. Then the nuclear radius of a nucleus with nucleon number 128 is

View answer and explanation

Correct option: C

6\mathrm{ } \times \mathrm{ }10{\;^{ - 15}}m

Option C (

6\mathrm{ } \times \mathrm{ }10{\;^{ - 15}}m

) is correct because the nuclear radius is proportional to the cube root of the nucleon number.

19 Medium

19 of 210

Remembering +4 | -1

Mean life of neutron is about

View answer and explanation

Correct option: B

\begin{array}{llllllllllllllllllll} {\mathrm{1000 }\,\mathrm{seconds}} \end{array}

Option B (1000 seconds) is correct because the mean lifetime of a free neutron is approximately 1000 seconds.

20 Medium

20 of 210

Understanding +4 | -1

Pick out the unmatched pair from the following

View answer and explanation

Correct option: D

Safety rods – Carbon

Option D (Safety rods – Carbon) is the unmatched pair because safety rods in nuclear reactors are typically made of materials like cadmium or boron, which are strong neutron absorbers, not carbon.

21 Medium

21 of 210

Analyzing +4 | -1

{\mathbf{F}_{pe}}

represents electrical force on proton due to electron and

{\mathbf{F}_{ep}}

on electron due to proton in a hydrogen atom.Similarly

{\mathbf{F}_{pe}}

represents the gravitational force on proton due to electron and

{\mathbf{F}_{ep}}

the corresponding force on electron due to proton. Which of the following is not true?

View answer and explanation

Correct option: D

{\mathbf{F}_{Pe}} + \mathbf{F'}{\,_{Pe}} = 0

Option D (

{\mathbf{F}_{Pe}} + \mathbf{F'}{\,_{Pe}} = 0

) is not true because the electric and gravitational forces between the proton and electron are not equal in magnitude.

22 Medium

22 of 210

Understanding +4 | -1

The binding energy per nucleon for the parent nucleus is

{E_1}

and that for the daughter nuclei is

{E_2}

. Then

View answer and explanation

Correct option: C

{E_2} > {E_1}

Option C (

{E_2} > {E_1}

) is correct because daughter nuclei are more stable and have higher binding energy per nucleon than the parent nucleus.

23 Medium

23 of 210

Application +4 | -1

The mass defect in particular nuclear reaction if

\mathrm{0}\mathrm{.3}\,\,\mathrm{g}

. The amount of energy liberated in kilowatt hour is (Velocity of light

= 3\,\, \times \,\,{10^8}\,\,\mathrm{m}{\mathrm{s}^{ - 1}}

View answer and explanation

Correct option: D

7.5\,\, \times \,\,{10^6}

Option D (

7.5\, \times \,{10^6}

) is correct because the energy liberated is calculated using

E=mc^2

and then converted to kilowatt-hours.

24 Easy

24 of 210

Understanding +4 | -1

Statement-1: The mass per nucleon in a hydrogen atom is the same as the in an oxygen atom.
Statement-2: The energy released during the formation of nuclei of different atoms from their constituent nuclei is different.

View answer and explanation

Correct option: D

Statement-1 is false, Statement-2 is true

Option D (Statement-1 is false, Statement-2 is true) is correct because the mass per nucleon varies between hydrogen and oxygen, and the energy released during nuclei formation differs.

25 Easy

25 of 210

Application +4 | -1

What would be the possible no. of elements if in nature elements with principal quantum number

n>4

were not allowed?

View answer and explanation

Correct option: A

Option A is correct because the number of elements is determined by the number of possible electron configurations, which is limited by the principal quantum number n. When n > 4 is not allowed, we sum the number of elements for n=1 to n=4.

26 Easy

26 of 210

Analyzing +4 | -1

The graph of

\ln \left(\frac{R}{R_0}\right)

versus

\ln A

(R=

radius of a nucleus and

A=

its mass number) is:

View answer and explanation

Correct option: A

a straight line

Option A (a straight line) is correct because the radius of a nucleus is proportional to A^(1/3), leading to a linear relationship between ln(R/R0) and ln(A).

27 Hard

27 of 210

Application +4 | -1

The half life of a radioactive substance is 20 minutes the time taken between 50% decay and 87.5% decay of the substance will be

View answer and explanation

Correct option: C

40 min

Option C (40 min) is correct because it is the time difference between the two decay percentages, calculated using the half-life concept.

28 Hard

28 of 210

Application +4 | -1

A radioactive sample disintegrates by

10 \%

during one month. How much fraction will disintegrate in four months :-

View answer and explanation

Correct option: A

34.39 \%

Option A (34.39 %) is correct because it calculates the fraction disintegrated after four months, given a 10% disintegration in one month.

29 Easy

29 of 210

Understanding +4 | -1

Which of the following is more effective for producing nuclear reactions with nuclei compared to protons?

View answer and explanation

Correct option: A

neutrons

Option A (neutrons) is correct because neutrons, being electrically neutral, are not repelled by the positively charged nucleus, making them more effective at penetrating the nucleus and causing nuclear reactions.

30 Medium

30 of 210

Application +4 | -1

A nuclear transformation is denoted by

X\,\,(n,\alpha ) \to {}_3^7\,\,\mathrm{Li}

. Which of the following is the nucleus of element

X

View answer and explanation

Correct option: B

{}_5^{10}\mathrm{B}

Option B (

{}_5^{10}\mathrm{B}

) is correct because, in the nuclear transformation, the mass and atomic numbers must be conserved.

Revision notes and key takeaways

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Key Takeaways

✓ This set contains 210 single-correct-answer MCQs on NUCLEI.
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