NEET Structure of Atom — Set 20

Question 1

An electron in $ \text{C}^{5+} $ has an angular momentum of $ 4.22 \times 10^{-34} \, \text{J s} $. What is its kinetic energy? ($ h = 6.626 \times 10^{-34} \, \text{J s} $, $ m_e = 9.1 \times 10^{-31} \, \text{kg} $, $ v_1 $ for H = $ 2.19 \times 10^6 \, \text{m s}^{-1} $)

Accepted Answer

$ n = \frac{L \cdot 2\pi}{h} = \frac{4.22 \times 10^{-34} \times 2 \times 3.14}{6.626 \times 10^{-34}} = 4 $. For $ \text{C}^{5+} $ (Z = 6), $ v_4 = 6 \times 2.19 \times 10^6 / 4 = 3.285 \times 10^6 \, \text{m s}^{-1} $. $ KE = \frac{1}{2} m v^2 = \frac{1}{2} \times 9.1 \times 10^{-31} \times (3.285 \times 10^6)^2 = 4.91 \times 10^{-18} \, \text{J} $.

Question 2

How many electrons in an atom can have $ n = 3 $ and $ l = 2 $?

Accepted Answer

For $ l = 2 $ (d subshell), number of orbitals = $ 2l + 1 = 5 $. Total electrons = $ 5 \times 2 = 10 $.

Question 3

How many electrons can have the quantum numbers $ n = 2, l = 0 $ in an atom?

Accepted Answer

For $ n = 2, l = 0 $ (2s subshell), number of orbitals = $ 2l + 1 = 1 $. Electrons = $ 1 \times 2 = 2 $.

NEET Chemistry: Structure of Atom — Practice Set 20

Q1. An electron in \( \text{C}^{5+} \) has an angular momentum of \( 4.22 \times 10^{-34} \, \text{J s} \). What is its kinetic energy? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \), \( v_1 \) for H = \( 2.19 \times 10^6 \, \text{m s}^{-1} \))

Q2. How many electrons in an atom can have \( n = 3 \) and \( l = 2 \)?

Q3. How many electrons can have the quantum numbers \( n = 2, l = 0 \) in an atom?

Q4. The number of spectral lines produced when an electron falls from \( n = 8 \) to \( n = 4 \) in a hydrogen atom is:

Q5. An electron in the fourth orbit of a hydrogen atom has a velocity of \( 5.475 \times 10^5 \, \text{m s}^{-1} \). What is its de Broglie wavelength? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

Q6. The frequency of a photon emitted during a transition from \( n = 7 \) to \( n = 4 \) in a hydrogen atom is: (\( E_1 = -2.18 \times 10^{-18} \, \text{J} \), \( h = 6.626 \times 10^{-34} \, \text{J s} \))

Q7. What is the maximum number of emission lines when an electron in a hydrogen atom drops from \( n = 5 \) to the ground state?

Q8. The uncertainty in velocity of an electron is \( 1.0 \times 10^6 \, \text{m s}^{-1} \). What is the minimum uncertainty in its position? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

Q9. A photon of energy \( 6.626 \times 10^{-19} \, \text{J} \) ejects an electron from a metal with a kinetic energy of \( 2.0 \times 10^{-19} \, \text{J} \). What is the stopping potential of the electron? (\( e = 1.6 \times 10^{-19} \, \text{C} \))

Q10. The ratio of the radii of the third orbit of \( \text{He}^+ \) to the second orbit of \( \text{Li}^{2+} \) is: (\( r_1 \) for H = \( 5.29 \times 10^{-11} \, \text{m} \))