NEET Structure of Atom — Set 4

Question 1

The frequency of a photon emitted during a transition from $ n = 6 $ to $ n = 3 $ in a hydrogen atom is: ($ E_1 = -2.18 \times 10^{-18} \, \text{J} $, $ h = 6.626 \times 10^{-34} \, \text{J s} $)

Accepted Answer

$ E_3 = -2.18 \times 10^{-18} / 9 = -2.422 \times 10^{-19} \, \text{J} $, $ E_6 = -2.18 \times 10^{-18} / 36 = -6.056 \times 10^{-20} \, \text{J} $. $ \Delta E = -6.056 \times 10^{-20} - (-2.422 \times 10^{-19}) = 1.8164 \times 10^{-19} \, \text{J} $. $ v = \frac{\Delta E}{h} = \frac{1.8164 \times 10^{-19}}{6.626 \times 10^{-34}} = 2.741 \times 10^{14} \, \text{Hz} $.

Question 2

How many orbitals are present in the $ n = 3 $ energy level of an atom?

Accepted Answer

Number of orbitals = $ n^2 $. For $ n = 3 $, $ 3^2 = 9 $ (3s: 1, 3p: 3, 3d: 5).

Question 3

The ratio of the velocities of an electron in the first orbit of $ \text{H} $ to the second orbit of $ \text{He}^+ $ is: ($ v_1 $ for H = $ 2.19 \times 10^6 \, \text{m s}^{-1} $)

Accepted Answer

For $ \text{H} $ (Z = 1), $ v_1 = 2.19 \times 10^6 \, \text{m s}^{-1} $. For $ \text{He}^+ $ (Z = 2), $ v_n = \frac{Z v_1}{n} $, $ v_2 = \frac{2 \times 2.19 \times 10^6}{2} = 2.19 \times 10^6 \, \text{m s}^{-1} $. Ratio = $ \frac{2.19 \times 10^6}{2.19 \times 10^6} = 1 $.

NEET Chemistry: Structure of Atom — Practice Set 4

Q1. The frequency of a photon emitted during a transition from \( n = 6 \) to \( n = 3 \) in a hydrogen atom is: (\( E_1 = -2.18 \times 10^{-18} \, \text{J} \), \( h = 6.626 \times 10^{-34} \, \text{J s} \))

Q2. How many orbitals are present in the \( n = 3 \) energy level of an atom?

Q3. The ratio of the velocities of an electron in the first orbit of \( \text{H} \) to the second orbit of \( \text{He}^+ \) is: (\( v_1 \) for H = \( 2.19 \times 10^6 \, \text{m s}^{-1} \))

Q4. The ionization energy of \( \text{H} \) is \( 13.6 \, \text{eV} \). What is the energy required to excite an electron in \( \text{He}^+ \) from \( n = 2 \) to \( n = 4 \)?

Q5. A hydrogen atom emits a photon of wavelength \( 410.2 \, \text{nm} \). What is the energy difference between the initial and final states? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( c = 3.0 \times 10^8 \, \text{m s}^{-1} \))

Q6. A metal has a threshold frequency of \( 5.5 \times 10^{14} \, \text{Hz} \). What is the stopping potential when irradiated with light of frequency \( 8.0 \times 10^{14} \, \text{Hz} \)? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( e = 1.6 \times 10^{-19} \, \text{C} \))

Q7. The ionization energy of \( \text{Be}^{3+} \) from its ground state is how many times that of a hydrogen atom? (\( E_H = 13.6 \, \text{eV} \))

Q8. What is the wavenumber of light emitted when an electron in a hydrogen atom transitions from \( n = 4 \) to \( n = 2 \)? (\( R_H = 1.097 \times 10^7 \, \text{m}^{-1} \))

Q9. Which particle has the highest charge-to-mass ratio?

Q10. The angular momentum of an electron in the sixth orbit of \( \text{Li}^{2+} \) is \( 6.33 \times 10^{-34} \, \text{J s} \). What is its radius? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( r_1 \) for H = \( 5.29 \times 10^{-11} \, \text{m} \))