NEET Chemistry: Structure of Atom — Practice Set 15

Q1. The radius of the first Bohr orbit of a hydrogen atom is \( 5.29 \times 10^{-11} \, \text{m} \). What is the radius of the second Bohr orbit?

A. \( 2.116 \times 10^{-10} \, \text{m} \)
B. \( 1.058 \times 10^{-10} \, \text{m} \)
C. \( 5.29 \times 10^{-11} \, \text{m} \)
D. \( 4.232 \times 10^{-10} \, \text{m} \)

Q2. Which of the following particles has the longest de Broglie wavelength if all have the same velocity?

A. Proton
B. Neutron
C. Alpha particle
D. Electron

Q3. What is the de Broglie wavelength of an electron moving with a velocity of \( 2.0 \times 10^6 \, \text{m s}^{-1} \)? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A. \(1.82 \times 10^{-10} \, \text{m}\)
B. \(3.64 \times 10^{-10} \, \text{m}\)
C. \(5.46 \times 10^{-10} \, \text{m}\)
D. \(7.28 \times 10^{-10} \, \text{m}\)

Q4. Which set of quantum numbers is not possible for an electron?

A. \( n = 2, l = 1, m_l = 0, m_s = +1/2 \)
B. \( n = 3, l = 0, m_l = 0, m_s = -1/2 \)
C. \( n = 1, l = 1, m_l = 0, m_s = +1/2 \)
D. \( n = 4, l = 2, m_l = -2, m_s = -1/2 \)

Q5. The threshold wavelength of a metal is \( 500 \, \text{nm} \). What is its work function in joules? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( c = 3.0 \times 10^8 \, \text{m s}^{-1} \))

A. \( 6.626 \times 10^{-19} \, \text{J} \)
B. \( 3.9756 \times 10^{-19} \, \text{J} \)
C. \( 2.6504 \times 10^{-19} \, \text{J} \)
D. \( 1.9878 \times 10^{-19} \, \text{J} \)

Q6. A photon of energy \( 5.0 \times 10^{-19} \, \text{J} \) strikes a metal with a work function of \( 3.5 \times 10^{-19} \, \text{J} \). What is the velocity of the ejected electron? (\( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A. \( 5.74 \times 10^5 \, \text{m s}^{-1} \)
B. \( 8.12 \times 10^5 \, \text{m s}^{-1} \)
C. \( 4.06 \times 10^5 \, \text{m s}^{-1} \)
D. \( 1.095 \times 10^6 \, \text{m s}^{-1} \)

Q7. The angular momentum of an electron in the fourth orbit of a hydrogen atom is \( 4.22 \times 10^{-34} \, \text{J s} \). What is its energy in eV? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( 1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J} \))

A. \( -3.4 \, \text{eV} \)
B. \( -1.51 \, \text{eV} \)
C. \( -13.6 \, \text{eV} \)
D. \( -0.85 \, \text{eV} \)

Q8. The wavelength of the third line in the Pfund series of a hydrogen atom is: (\( R_H = 1.097 \times 10^7 \, \text{m}^{-1} \))

A. \( 4654 \, \text{nm} \)
B. \( 2279 \, \text{nm} \)
C. \( 3741 \, \text{nm} \)
D. \( 1876 \, \text{nm} \)

Q9. The kinetic energy of an electron in the third orbit of \( \text{Be}^{3+} \) is \( 2.42 \times 10^{-18} \, \text{J} \). What is its velocity? (\( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A. \( 2.19 \times 10^6 \, \text{m s}^{-1} \)
B. \( 1.095 \times 10^6 \, \text{m s}^{-1} \)
C. \( 2.306 \times 10^6 \, \text{m s}^{-1} \)
D. \( 4.38 \times 10^6 \, \text{m s}^{-1} \)

Q10. An electron and a proton have the same de Broglie wavelength. What is the ratio of their kinetic energies? (\( m_p = 1.67 \times 10^{-27} \, \text{kg} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A. 1
B. 1836
C. 918
D. 0.00054

Chemistry — Structure of Atom

Set 15 of 20

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The radius of the first Bohr orbit of a hydrogen atom is \( 5.29 \times 10^{-11} \, \text{m} \). What is the radius of the second Bohr orbit?

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