On account of the disruption in education due to the corona pandemic, we're opening up our platform for teachers, free of cost. Know More →

NEET

Explore popular questions from Atoms and Nuclei for NEET. This collection covers Atoms and Nuclei previous year NEET questions hand picked by experienced teachers.

Select Subject

Physics

Chemistry

Biology

Atoms and Nuclei

Correct Marks 4

Incorrectly Marks -1

Q 1. The potential energy associated with an electron in the orbit

increases with the increases in radii of the orbit

B

decreases with the increase in the radii of the orbit

C

remains the same with the change in the radii of the orbit

D

None of these

Correct Marks 4

Incorrectly Marks -1

Q 2. The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

A

{tex} \mathrm {IV } {/tex}

{tex}\mathrm{III} {/tex}

C

{tex}\mathrm{II}{/tex}

D

{tex}\mathrm{I}{/tex}

Explanation

The energy diagram is drawn with appropriate scale to indicate difference in energy levels. The largest energy difference between states is between 1 and 2. 1 wouldn't release a photon, it would absorb energy. The largest jump releasing energy would be the 3rd.

Correct Marks 4

Incorrectly Marks -1

Q 3. Electrons in a certain energy level {tex} n = n _ { 1 } , {/tex} can emit 3 spectral lines. When they are in another energy level, {tex} n = n _ { 2 } . {/tex} They
can emit 6 spectral lines. The orbital speed of the electrons in the two orbits are in the ratio of

{tex} 4 : 3 {/tex}

B

{tex} 3 : 4 {/tex}

C

{tex} 2 : 1 {/tex}

D

{tex} 1 : 2 {/tex}

Explanation





Correct Marks 4

Incorrectly Marks -1

Q 4. A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. It will emit:

2 lines in the Lyman series and 1 line in the Balmar series

B

3 lines in the Lyman series

C

1 line in the Lyman series and 2 lines in the Balmar series

D

3 lines in the Balmer series

Explanation








Correct Marks 4

Incorrectly Marks -1

Q 5. The radius of hydrogen atom in its ground state is {tex} 5.3 \times 10 ^ { - 11 } \mathrm { m } . {/tex} After collision with an electron it is found to
have a radius of {tex} 21.2 \times 10 ^ { - 11 } \mathrm { m } {/tex} . What is the principal quantum number {tex} \mathrm { n } {/tex} of the final state of the atom

A

{tex} n = 4 {/tex}

{tex} n = 2 {/tex}

C

{tex} n = 16 {/tex}

D

{tex} n = 3 {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 6. When hydrogen atom is in its first excited level, its radius is

four times its ground state radius

B

twice

C

same

D

half

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 7. Consider {tex} 3 ^ { \text {rd } } {/tex} orbit of {tex} \mathrm { He } ^ { + } {/tex} (Helium), using non-relativistic approach, the speed of electron in this orbit will be {tex} [ \text {given } \mathrm { K } {/tex}
{tex} = 9 \times 10 ^ { 9 } {/tex} constant {tex} , Z = 2 {/tex} and {tex} h {/tex} (Plank's Constant) {tex} \left. = 6.6 \times 10 ^ { - 34 } \mathrm { Js } \right] {/tex}

{tex} 1.46 \times 10 ^ { 6 } \mathrm { m } / \mathrm { s } {/tex}

B

{tex} 0.73 \times 10 ^ { 6 } \mathrm { m } / \mathrm { s } {/tex}

C

{tex} 3.0 \times 10 ^ { 8 } \mathrm { m } / \mathrm { s } {/tex}

D

{tex} 2.92 \times 10 ^ { 6 } \mathrm { m } / \mathrm { s } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 8. An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function {tex}2.75 \mathrm {eV}{/tex}. If the stopping potential of the photoelectron is {tex} 10 \mathrm { V } , {/tex} the value of {tex} \mathrm { n } {/tex} is

A

3

4

C

5

D

2

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 9. The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true?

Its kinetic energy increases

B

Its kinetic energy decreases

C

Time period increases

D

None of the above

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 10. An energy of 24.6eV is required to remove one of the electrons from a neutral helium atom. The energy in (eV)required to remove both the electrons from a neutral helium atom is

A

38.2

B

49.2

C

51.8

79

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 11. One of the lines in the emission spectrum of {tex} \mathrm { Li } ^ { 2 + } {/tex} has the same wavelength as that of the {tex} 2 ^ { \text {nd } } {/tex} line of Balmer series in
hydrogen spectrum. The electronic transition corresponding to this line is {tex} \mathrm { n } = 12 \rightarrow \mathrm { n } = \mathrm { x } {/tex} . Find the value of {tex} \mathrm { x } {/tex} .

A

8

6

C

7

D

5

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 12. If the atom {tex} _ { 100 } \mathrm {F m} ^ { 257 } {/tex} follows the Bohr model and the radius of {tex} _ { 100 } \mathrm { Fm } ^ { 257 } {/tex} is {tex} n {/tex} times the Bohr radius, then find {tex} n {/tex}

A

100

B

200

C

4

{tex}1 / 4 {/tex}

Explanation

Therefore, {tex} r_m {/tex} = {tex} \frac {r_0 5 ^ {2}}{100} {/tex} = {tex} nr_0 {/tex} ⇒ {tex} n = {/tex} {tex} \frac {1}{4} {/tex}

Correct Marks 4

Incorrectly Marks -1

Q 13. The ionization energy of hydrogen atom is {tex}13.6\mathrm { eV}{/tex}. Following Bohr's theory, the energy corresponding to a transition between 3{tex} \mathrm { rd } {/tex} and 4{tex} \mathrm { th } {/tex} orbit is {tex} \mathrm { K } = 9 \times 10 ^ { 9 } {/tex} constant, {tex} \mathrm { Z } = 2 {/tex} and {tex} \mathrm { h } {/tex} (Plank's Constant) {tex} \left. = 6.6 \times 10 ^ { - 34 } \mathrm { Js } \right] {/tex}

A

3.40{tex} \mathrm { eV } {/tex}

B

1.51{tex} \mathrm { eV } {/tex}

C

0.85{tex} \mathrm { eV } {/tex}

0.66{tex} \mathrm { eV } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 14. The transition from the state {tex} n = 3 {/tex} to {tex} n = 1 {/tex} in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from:

A

{tex} 2\rightarrow 1 {/tex}

B

{tex} 4\rightarrow 2 {/tex}

C

{tex} 4\rightarrow 2 {/tex}

{tex} 4\rightarrow 3 {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 15. Given the value of Rydberg constant is {tex} 10 ^ { 7 } \mathrm { m } ^ { - 1 } {/tex} , the wave number of the last line of the Balmer series in hydrogen spectrum will be:

A

{tex} 0.025 \times 10 ^ { 4 } \mathrm { m } ^ { - 1 } {/tex}

B

{tex} 0.5 \times 10 ^ { 7 } \mathrm { m } ^ { - 1 } {/tex}

{tex} 0.25 \times 10 ^ { 7 } \mathrm { m } ^ { - 1 } {/tex}

D

{tex} 2.5 \times 10 ^ { 7 } \mathrm { m } ^ { - 1 } {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 16. The ionisation potential of H-atom is 13.6{tex} \mathrm { V } {/tex} . When it is excited from ground state by monochromatic radiations of 970.6{tex}{\text{Å}}{/tex} the number of emission lines will be (according to Bohr's theory)

A

10

B

8

6

D

4

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 17. The energy of hydrogen atom in nth orbit is {tex} E _ { n } , {/tex} then the energy in nth orbit of single ionised helium atom will be

{tex}4 E _ { n } {/tex}

B

{tex} E _ { n } / 4 {/tex}

C

{tex}2 E _ { n } {/tex}

D

{tex} E _ { n } / 2 {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 18. In the Rutherford experiment, {tex} \alpha {/tex} -particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible?

A

{tex} D {/tex}

B

{tex} B {/tex}

{tex} C {/tex}

D

{tex} A {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 19. In a Rutherford scattering experiment when a projectile of charge {tex} Z _ { 1 } {/tex} and mass {tex} M _ { 1 } {/tex} approaches a target nucleus of charge {tex} \mathrm { Z } _ { 2 } {/tex} and mass {tex} \mathrm { M } _ { 2 } , {/tex} the distance of closest approach is {tex} \mathrm { r } _ { 0 } . {/tex} The energy of the projectile is

directly proportional to {tex} \mathrm { Z } _ { 1 } \mathrm { Z } _ { 2 } {/tex}

B

inversely proportional to {tex} \mathrm { Z } _ { 1 } {/tex}

C

directly proportional to mass {tex} \mathrm { M } _ { 1 } {/tex}

D

directly proportional to {tex} \mathrm { M } _ { 1 } \times \mathrm { M } _ { 2 } {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 20. The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561Å. The wavelength of the second spectral line in the Balmer series of singly-ionized helium atom is

1215 Å

B

1640 Å

C

2430 Å

D

4687 Å

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 21. If {tex} v _ { 1 } {/tex} is the frequency of the series limit of Lyman series, {tex} v _ { 2 } {/tex} is the frequency of the first line of Lyman series and {tex} v _ { 3 } {/tex} is the frequency of the series limit of the Balmer series then

{tex} v _ { 1 } - v _ { 2 } = v _ { 3 } {/tex}

B

{tex} v _ { 1 } = v _ { 2 } - v _ { 3 } {/tex}

C

{tex} \frac { 1 } { { v } _ { 2 } } = \frac { 1 } { { v } _ { 1 } } + \frac { 1 } { { v } _ { 3 } } {/tex}

D

{tex} \frac { 1 } { v _ { 1 } } = \frac { 1 } { v _ { 2 } } + \frac { 1 } { v _ { 3 } } {/tex}

Explanation




Correct Marks 4

Incorrectly Marks -1

Q 22. In a hypothetical Bohr hydrogen atom, the mass of the electron is doubled. The energy E0 and radius r0 of the first orbit will be: (r0 is the Bohr radius)

A

{tex} - 11.2 \mathrm { eV } {/tex}

B

{tex} - 6.8 \mathrm { eV } {/tex}

C

{tex} - 13.6 \mathrm { eV } {/tex}

{tex} - 27.2 \mathrm { eV } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 23. The mass of a {tex} _{3} ^ { 7 } L i {/tex} nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of {tex} ^{ 7 } _{ 3 } L i {/tex} nucleus is nearly

A

46{tex} \mathrm { MeV } {/tex}

5.6{tex} \mathrm { MeV } {/tex}

C

3.9{tex} \mathrm { MeV } {/tex}

D

23{tex} \mathrm { MeV } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 24. In the nuclear decay given below:

the particles emitted in the sequence are

A

{tex} \gamma , \beta , \alpha {/tex}

B

{tex} \beta , \gamma , \alpha {/tex}

C

{tex} \alpha , \beta , \gamma {/tex}

{tex} \beta , \alpha , \gamma {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 25. If the nuclear radius of {tex} ^ { 27 } \mathrm { Al } {/tex} is 3.6 Fermi , the approximate nuclear radius of {tex} ^ { 64 } \mathrm { Cu } {/tex} in Fermi is:

A

2.4

B

12

4.8

D

3.6

Explanation