neet physics tutor doubt 5 - Atoms, Nuclei and Semiconductors NEET MCQs

Question 1. In a nuclear reaction, the β^- particle is emitted

1. After de-excitation of a nucleus
2. After ionization of an atom
3. Due to conversion of a neutron into a proton
4. Due to conversion of a proton into a neutron

Question 2. What is the potential energy of the electron in an orbit of radius r in the hydrogen atom? (e = charge of electron)

1. K e²/r
2. -K e²/r
3. K e²2r
4. -K e²2r

Question 3. The binding energy of deuteron is 2.5 MeV and that of ⁴He is 26 MeV. If two deuterons are fused to form one ⁴He, then energy released in the process will be

1. 12 MeV
2. 84 MeV
3. 21 MeV
4. 6 MeV

Question 4. The total energy of electron in the He⁺ atom in first excited state is -13.6 eV. The kinetic energy of this electron will be

1. 13.6 eV
2. 54.4 eV
3. 3.4 eV
4. 27.2 eV

Question 5. The electrical conductivity of pure silicon can be increased by

1. Increasing the temperature
2. Decreasing the temperature
3. Doping acceptor impurity
4. Both (1) and (3)

Question 6. Match Column-I and Column-II.

1. (i) → c; (ii) → b; (iii) → a; (iv) → d
2. (i) → b; (ii) → c; (iii) → a; (iv) → d
3. (i) → c; (ii) → b; (iii) → d; (iv) → a
4. (i) → c; (ii) → d; (iii) → b; (iv) → a

Question 7. Following diagram performs the logic function of

1. NOR gate
2. NAND gate
3. AND gate
4. OR gate

Question 8. Which of the following statements is/are correct?

1. Pure Ge doped with pentavalent impurities gives an N-type semiconductor.
2. Minority carriers in an N-type semiconductor are electrons.
3. N-type semiconductor is negatively charged.
4. P-type semiconductor is positively charged.

1. (i) only
2. (ii), (iii) and (iv)
3. (i) and (ii)
4. (i), (iii) and (iv)

Question 9. Which of the following is correct for Zener diode?

1. It is fabricated by lightly doping both P and N sides of the junction
2. It is designed to operate in forward bias condition
3. It is used for regulating voltage
4. It offers infinite resistance in reverse bias condition

Question 10. In the given circuit, the current through the battery is (all diodes are ideal).

1. 1 A
2. 1.2 A
3. 2 A
4. 3 A

Question 11. If kinetic energy of an electron in first orbit of hydrogen atom is K, then potential energy of an electron in first orbit of singly ionized helium atom is

1. -2K
2. -4K
3. -8K
4. -16K

Question 12. The output current versus time curve of a half wave rectifier for sinusoidal input is shown in the figure. The average value of the output current in this case is

1. Zero
2. i₀/π
3. 2i₀/π
4. i₀

Question 13. The shape of meniscus when contact angle is less than 90° is

1. Concave downwards
2. Concave upwards
3. Can either be concave downwards or concave upwards
4. Insufficient information

Question 14. Assertion (A): In general, heavier nuclides contain more number of neutrons than protons. Reason (R): To overcome the coulombic repulsion between protons, more number of neutrons are required. In the light of above statements, choose the correct option.

1. Both (A) and (R) are true and (R) is the correct explanation of (A)
2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false

Question 15. Consider the following statements regarding nuclear force and select the correct statement(s).

1. They are independent of charge.
2. They are always attractive in nature.
3. They are non-central forces.

1. I only
2. I and II
3. I and III
4. I, II and III

Question 16. A nucleus of ₉₂U²³⁸ originally at rest emits an α-particle with speed v₀. The speed of daughter nucleus will be

1. v₀127
2. 2v₀117
3. 2v₀127
4. v₀117

Question 17. If the metre scale shown below is in rotational equilibrium, then the unknown weight W will be equal to

1. 12 N
2. 15 N
3. 20 N
4. 30 N

Question 18. A potential barrier of 0.60 V exists across P-N junction. If the depletion region is 3 × 10^-5 m wide, then the intensity of the electric field in this region is

1. 10⁴ V/m
2. 2 × 10⁴ V/m
3. 10⁶ V/m
4. 2 × 10⁶ V/m

Question 19. The mass of a ¹¹B nucleus is 0.077 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of ¹¹B nucleus is (given, 1 u × c² = 930 MeV)

1. 71.61 MeV
2. 65.11 MeV
3. 7.16 MeV
4. 6.51 MeV

Question 20. When radiation of wavelength λ is incident on a metallic surface, the stopping potential is 3 volt. If the same surface is irradiated with radiation of double wavelength, then the stopping potential becomes 1 volt. The work function of the metal is

1. 2 eV
2. 0.5 eV
3. 1.5 eV
4. 1 eV

Question 21. A particle of mass 9 × 10^-25 kg has the same de-Broglie wavelength as an electron moving with a velocity of 4 × 10⁶ m s^-1. The velocity of the particle is (given, mass of electron = 9 × 10^-31 kg)

1. 18 m s^-1
2. 4 m s^-1
3. 9 m s^-1
4. 2 m s^-1

Question 22. In a photoelectric experiment, the frequency and photon intensity of the light source are both quadrupled. Consider the following statements.

1. The saturation photocurrent remains almost the same.
2. The maximum kinetic energy of the photoelectrons is quadrupled.

1. (i) is true but (ii) is false
2. (i) is false but (ii) is true
3. Both (i) and (ii) are true
4. Both (i) and (ii) are false

Question 23. In a hypothetical atom, if transition from n = 5 to n = 3 produces visible light then the possible transition to obtain infrared radiation is

1. n = 5 to n = 2
2. n = 3 to n = 2
3. n = 6 to n = 3
4. n = 6 to n = 4

Question 24. For an equilateral triangular prism, if angle of minimum deviation is δ_m, then refractive index μ is equal to

1. 12 sin(30° + δ_m2)
2. 12 sin(15° + δ_m2)
3. 2 sin(30° + δ_m2)
4. 2 sin(15° + δ_m2)

Question 25. The ratio of radii of first shell of H-atom to that of third shell of Li⁺⁺ ion is

1. 1 : 2
2. 1 : 9
3. 1 : 3
4. 1 : 27

Question 26. An α-particle is bombarded on ₇N¹⁴ nucleus and a proton is emitted. The product nucleus is

1. ₅B¹⁰
2. ₆C¹³
3. ₈O¹⁷
4. ₇N¹³

Question 27. The speed of electron in second stable orbit of hydrogen atom is (c is speed of light in vacuum)

1. c137
2. c274
3. c548
4. c685

Question 28. Consider the following statements A and B and identify the correct answer.

A. Fission is the source of energy of all stars including our sun.

B. In fusion, lighter nuclei combine to form a larger nucleus.

1. A is correct but B is incorrect
2. A is incorrect but B is correct
3. Both A and B are correct
4. Both A and B are incorrect

Question 29. 1 cm on the main scale of vernier callipers is divided into 10 equal parts. If 20 divisions of vernier scale coincide with 18 divisions of main scale, then least count of callipers is

1. 1 cm
2. 0.1 cm
3. 0.01 cm
4. 0.02 cm

Question 30. The energy required to remove an electron from fourth orbit of hydrogen atom is

1. 13.6 eV
2. 3.4 eV
3. 1.51 eV
4. 0.85 eV

Question 31. The energy of emitted photon when an electron jumps from third orbit to first orbit in a hydrogen atom is

1. 12.08 eV
2. 13.6 eV
3. 1.51 eV
4. 10.2 eV

Question 32. The photoelectrons emitted from the surface of metal are such that they

1. Have same kinetic energy
2. Have same velocity
3. Have same de-Broglie wavelength
4. Have their speeds varying from zero to a certain maximum value

Question 33. An external voltage V is applied across a diode such that it is reverse biased. As the reverse bias voltage is gradually increased before it reaches breakdown voltage, then current

1. Sharply increases
2. Sharply decreases
3. First increases and then decreases
4. Remains voltage independent

Question 34. In an experiment to determine the resistance of galvanometer by half-deflection method, we use the following circuit where R = 600 Ω and G = 3 Ω. Then the value of resistance S is (where symbols have their usual meaning)

1. 600201 Ω
2. 3 Ω
3. 600199 Ω
4. 2 Ω

Question 35. The ratio of velocities of deuteron and α-particle, if the de-Broglie wavelength of both the particles is same, will be

1. 2 : 1
2. 4 : 1
3. √2 : 1
4. 1 : √3

Question 36. In a hypothetical fission reaction ₉₂X²³⁶ → ₅₆Y¹⁴¹ + ₃₅Z⁹³ + ₀n¹ + R, the identity of emitted particle R is

1. Proton
2. Electron
3. Neutron
4. α-particle

Question 37. A beam of light consists of two wavelengths λ and 2λ, and the number of photons passing in unit time for the two wavelengths are 2n and 3n respectively. If the cross-sectional area of the beam is A, then intensity of the light beam will be

1. 3nhcλA
2. 7nhc2λA
3. 3nhc2λA
4. 5nhc2λA

Question 38. A metal plate is irradiated with a certain wavelength of radiation. If all the electrons ejected from the metal plate can be stopped before travelling 2 m in the direction of uniform electric field of 3 N/C, then the possible value(s) of kinetic energy of the ejected electrons is/are

1. 1 eV
2. 2 eV
3. 7 eV
4. Both (1) and (2)

Question 39. Consider the following statements and choose the correct statement(s):

1. The stopping potential increases with increase in frequency of incident light.
2. The saturation photocurrent increases with intensity of light.
3. The work function of emitter plate decreases with decrease in frequency of incident light.

1. (III) only
2. (II) only
3. (I) and (II)
4. (I) and (III)

Question 40. The time of revolution of an electron around a nucleus of atomic number Z in nth Bohr’s orbit is directly proportional to

1. n²Z
2. n³Z²
3. n²Z²
4. n³Z

Question 41. The radius of nuclei X is measured to be twice the radius of nuclei Y. The ratio of nucleons in X to Y is

1. 8 : 1
2. 2 : 1
3. 1 : 4
4. 1 : 1

Question 42. The ratio of the shortest wavelength of Paschen series to the shortest wavelength of Lyman series for hydrogen atom is

1. 1 : 9
2. 9 : 1
3. 9 : 4
4. 4 : 9

Question 43. The acceptor level of a p-type semiconductor is 5 eV. The maximum wavelength of light which can create a hole would be (given, hc = 12400 eV Å)

1. 2480 Å
2. 1240 Å
3. 4960 Å
4. 248 Å

Question 44. A screw gauge has 50 equal divisions marked on its circular scale and one full rotation of the circular scale advances the main scale by 0.02 cm. The least count of this screw gauge is

1. 2 × 10^-4 cm
2. 4 × 10^-4 cm
3. 3 × 10^-4 cm
4. 4 × 10^-3 cm

Question 45. In a resonance tube experiment, first resonating length is 15 cm and second resonating length is 47 cm, then wavelength of the wave is

1. 16 cm
2. 32 cm
3. 64 cm
4. 48 cm

Question 46. Hydrogen gas sample in ground state is given an energy of 12.75 eV. How many spectral lines will be emitted due to transition of electrons?

1. 1
2. 3
3. 6
4. 10

Question 47. In the circuit shown, if the potential drop in forward bias condition across Si and Ge diodes are 0.7 V and 0.3 V respectively, then the potential difference across 2 kΩ resistor is

1. 11.4 V
2. 7.6 V
3. 8 V
4. 12 V

Question 48. If M₀ is the mass of nucleus ¹²C, M_p and M_n are the masses of proton and neutron, then nuclear binding energy of nucleus ¹²C is

1. (6M_p + 6M_n - M₀)c²
2. (M₀ - 12M_p)c²
3. (M₀ - 12M_n)c²
4. (M₀ - 6M_n + 6M_p)c²

Question 49. A proton, a deuteron and an electron have the same kinetic energies. Their de-Broglie wavelengths will be compared as

1. λ_e < λ_d < λ_p
2. λ_e < λ_p < λ_d
3. λ_e > λ_d > λ_p
4. λ_e > λ_p > λ_d

Question 50. The de-Broglie wavelength of a particle accelerating with 130 V potential is 1 Å. If the accelerating potential is increased to 520 V, then its de-Broglie wavelength will be

1. 1 Å
2. 0.25 Å
3. 0.5 Å
4. 2 Å