NEET Chemistry: Structure of Atom — Practice Set 11 (10 MCQs)

NEET Chemistry: Structure of Atom — Practice Set 11

Q1. The radius of the second orbit of a hydrogen atom is \( 2.116 \times 10^{-10} \, \text{m} \). What is the velocity of the electron in the fourth orbit? (\( v_1 \) for H = \( 2.19 \times 10^6 \, \text{m s}^{-1} \))

A. \( 1.095 \times 10^6 \, \text{m s}^{-1} \)
B. \( 5.475 \times 10^5 \, \text{m s}^{-1} \)
C. \( 7.3 \times 10^5 \, \text{m s}^{-1} \)
D. \( 2.19 \times 10^6 \, \text{m s}^{-1} \)

Q2. The ionization energy of \( \text{Li}^{2+} \) from its ground state is how many times that of a hydrogen atom? (\( E_H = 2.18 \times 10^{-18} \, \text{J} \))

A. 4
B. 6
C. 3
D. 9

Q3. Which of the following has the same number of neutrons as \( ^{40}_{18}\text{Ar} \)?

A. \( ^{39}_{19}\text{K} \)
B. \( ^{42}_{20}\text{Ca} \)
C. \( ^{41}_{19}\text{K} \)
D. \( ^{40}_{20}\text{Ca} \)

Q4. A metal has a work function of \( 2.5 \, \text{eV} \). What is the threshold wavelength? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( c = 3.0 \times 10^8 \, \text{m s}^{-1} \), \( 1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J} \))

A. \( 620.5 \, \text{nm} \)
B. \( 354.2 \, \text{nm} \)
C. \( 443.7 \, \text{nm} \)
D. \( 496.95 \, \text{nm} \)

Q5. The uncertainty in position of a proton is \( 1.5 \times 10^{-11} \, \text{m} \). What is the minimum uncertainty in its momentum? (\( h = 6.626 \times 10^{-34} \, \text{J s} \))

A. \( 1.76 \times 10^{-24} \, \text{kg m s}^{-1} \)
B. \( 5.27 \times 10^{-24} \, \text{kg m s}^{-1} \)
C. \( 3.52 \times 10^{-24} \, \text{kg m s}^{-1} \)
D. \( 2.64 \times 10^{-24} \, \text{kg m s}^{-1} \)

Q6. An electron in the third orbit of a hydrogen atom has a velocity of \( 7.3 \times 10^5 \, \text{m s}^{-1} \). What is its de Broglie wavelength? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A. \( 9.98 \times 10^{-10} \, \text{m} \)
B. \( 4.99 \times 10^{-10} \, \text{m} \)
C. \( 6.65 \times 10^{-10} \, \text{m} \)
D. \( 1.33 \times 10^{-9} \, \text{m} \)

Q7. Which of the following has the same number of electrons as \( \text{Ar} \) (atomic number 18)?

A. \( \text{Na}^+ \)
B. \( \text{Mg}^{2+} \)
C. \( \text{K}^+ \)
D. \( \text{Ca}^{2+} \)

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

A. \( 2.437 \times 10^6 \, \text{m}^{-1} \)
B. \( 1.523 \times 10^6 \, \text{m}^{-1} \)
C. \( 3.291 \times 10^6 \, \text{m}^{-1} \)
D. \( 2.057 \times 10^6 \, \text{m}^{-1} \)

Q9. Which of the following sets of quantum numbers is not permissible for an electron?

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

Q10. A metal has a work function of \( 2.8 \, \text{eV} \). What is the threshold wavelength? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( c = 3.0 \times 10^8 \, \text{m s}^{-1} \), \( 1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J} \))

A. \( 354.2 \, \text{nm} \)
B. \( 620.5 \, \text{nm} \)
C. \( 295.1 \, \text{nm} \)
D. \( 443.7 \, \text{nm} \)

Chemistry — Structure of Atom

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The radius of the second orbit of a hydrogen atom is \( 2.116 \times 10^{-10} \, \text{m} \). What is the velocity of the electron in the fourth orbit? (\( v_1 \) for H = \( 2.19 \times 10^6 \, \text{m s}^{-1} \))

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