# 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.

## Biology

Atoms and Nuclei

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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

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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.

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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}

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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