NEET Atoms and Nuclei — Set 8

Question 1

What is the frequency of a photon emitted when an electron drops from $ n = 2 $ to $ n = 1 $ in a hydrogen atom? (Use $ h = 6.6 \times 10^{-34} \, \text{J·s} $, 1 eV = $ 1.6 \times 10^{-19} \, \text{J} $)

Accepted Answer

$ \Delta E = 10.2 \, \text{eV} = 1.632 \times 10^{-18} \, \text{J} $. $ \nu = \frac{\Delta E}{h} = \frac{1.632 \times 10^{-18}}{6.6 \times 10^{-34}} \approx 2.47 \times 10^{15} \, \text{Hz} $.

Question 2

What is the frequency of a photon emitted when an electron drops from $ n = 3 $ to $ n = 1 $ in a hydrogen atom? (Use $ h = 6.6 \times 10^{-34} \, \text{J·s} $, 1 eV = $ 1.6 \times 10^{-19} \, \text{J} $)

Accepted Answer

$ \Delta E = 12.09 \, \text{eV} = 1.9344 \times 10^{-18} \, \text{J} $. $ \nu = \frac{\Delta E}{h} = \frac{1.9344 \times 10^{-18}}{6.6 \times 10^{-34}} \approx 2.93 \times 10^{15} \, \text{Hz} $.

Question 3

What assumption in Rutherford’s model contradicts classical electromagnetic theory?

Accepted Answer

Rutherford assumes electrons orbit the nucleus like planets, but classical theory predicts they would radiate energy and collapse, not remain stable.

NEET Physics: Atoms and Nuclei — Practice Set 8

Q1. What is the frequency of a photon emitted when an electron drops from \( n = 2 \) to \( n = 1 \) in a hydrogen atom? (Use \( h = 6.6 \times 10^{-34} \, \text{J·s} \), 1 eV = \( 1.6 \times 10^{-19} \, \text{J} \))

Q2. What is the frequency of a photon emitted when an electron drops from \( n = 3 \) to \( n = 1 \) in a hydrogen atom? (Use \( h = 6.6 \times 10^{-34} \, \text{J·s} \), 1 eV = \( 1.6 \times 10^{-19} \, \text{J} \))

Q3. What assumption in Rutherford’s model contradicts classical electromagnetic theory?

Q4. In Bohr’s model, what happens to the energy required to ionize a hydrogen atom as the electron’s orbit number increases?

Q5. In Rutherford’s scattering experiment, what causes the large deflection of some alpha-particles?

Q6. In a hydrogen atom, the total energy of an electron in the \( n = 3 \) state is -1.51 eV. What is its potential energy?

Q7. In the Bohr model, how many de Broglie wavelengths fit into the circumference of the \( n = 3 \) orbit?

Q8. Which of the following statements is correct about the absorption process in a hydrogen atom?

Q9. What is the orbital period of an electron in the \( n = 4 \) orbit if \( v_1 = 2.2 \times 10^6 \, \text{m/s} \) and \( r_1 = 5.3 \times 10^{-11} \, \text{m} \)?

Q10. What is a limitation of Bohr’s model when applied to the hydrogen atom’s spectrum?