NEET Physics: Atoms and Nuclei — Practice Set 4

Q1. Which of the following statements is incorrect about the hydrogen atom’s energy levels in Bohr’s model?

A. Energy is negative in bound states
B. Energy levels are discrete
C. Energy is positive in all orbits
D. Energy approaches zero as \( n \) increases

Q2. In Rutherford’s scattering experiment, what percentage of alpha-particles scatter by more than 1°?

A. 1.4%
B. 0.14%
C. 0.014%
D. 14%

Q3. What is the orbital period of an electron in the first orbit of a hydrogen atom if its speed is \( 2.2 \times 10^6 \, \text{m/s} \) and radius is \( 5.3 \times 10^{-11} \, \text{m} \)?

A. \( 1.0 \times 10^{-16} \, \text{s} \)
B. \( 1.2 \times 10^{-16} \, \text{s} \)
C. \( 1.8 \times 10^{-16} \, \text{s} \)
D. \( 1.51 \times 10^{-16} \, \text{s} \)

Q4. What is the angular momentum of an electron in the \( n = 2 \) state of a hydrogen atom? (Use \( h = 6.6 \times 10^{-34} \, \text{J·s} \))

A. \( 1.05 \times 10^{-34} \, \text{J·s} \)
B. \( 3.15 \times 10^{-34} \, \text{J·s} \)
C. \( 2.1 \times 10^{-34} \, \text{J·s} \)
D. \( 4.2 \times 10^{-34} \, \text{J·s} \)

Q5. What does the line spectrum of hydrogen indicate about its atomic structure?

A. Continuous energy distribution
B. Discrete energy levels
C. Uniform charge distribution
D. Random electron motion

Q6. Why did Rutherford’s nuclear model fail to explain the stability of atoms?

A. Nucleus was too small
B. Electrons had no charge
C. Accelerating electrons emit radiation
D. Positive charge was uniform

Q7. What is the orbital period of an electron in the \( n = 2 \) orbit of a hydrogen atom if \( v_1 = 2.2 \times 10^6 \, \text{m/s} \) and \( r_1 = 5.3 \times 10^{-11} \, \text{m} \)?

A. \( 1.51 \times 10^{-16} \, \text{s} \)
B. \( 6.05 \times 10^{-16} \, \text{s} \)
C. \( 3.02 \times 10^{-16} \, \text{s} \)
D. \( 1.21 \times 10^{-15} \, \text{s} \)

Q8. A photon of energy 10.2 eV is absorbed by a hydrogen atom in the ground state. To which energy level does the electron jump? (Use \( E_n = -\frac{13.6}{n^2} \, \text{eV} \))

A. 1
B. 3
C. 2
D. 4

Q9. What is the potential energy of an electron in the \( n = 5 \) state of a hydrogen atom? (Use \( E_n = -\frac{13.6}{n^2} \, \text{eV} \))

A. -0.544 eV
B. -0.85 eV
C. -1.09 eV
D. -3.4 eV

Q10. In an alpha-particle scattering experiment, a 5.5 MeV alpha-particle approaches a gold nucleus (Z = 79). What is the approximate distance of closest approach? (Take \( \frac{1}{4\pi\epsilon_0} = 9 \times 10^9 \, \text{N·m}^2/\text{C}^2 \), \( e = 1.6 \times 10^{-19} \, \text{C} \), 1 MeV = \( 1.6 \times 10^{-13} \, \text{J} \))

A. 40 fm
B. 45 fm
C. 50 fm
D. 55 fm

Physics — Atoms and Nuclei

Set 4 of 22

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Which of the following statements is incorrect about the hydrogen atom’s energy levels in Bohr’s model?

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