Q1. The energy of an electron in the first Bohr orbit of a hydrogen atom is −2.18 × 10⁻¹⁸ J. What will be the energy of the electron in the third Bohr orbit?
Q2. How many spectral lines are obtained in the emission spectrum of He⁺ ion when an electron makes a transition from the fifth excited state to the first excited state?
Q3. In an atom, the total number of electrons having quantum numbers n = 4, ml = +1 and ms = −1/2 is:
Q4. The wavelength of radiation is 5800 Å. The corresponding wavenumber (in cm⁻¹) is:
Q5. The minimum uncertainty in the speed of an electron confined to a region of length 2a₀ is closest to:
Q6. Statement I: A spectral line is observed for a 2px → 2py transition. Statement II: 2px and 2py are degenerate orbitals.
Q7. The longest wavelength of light required to ionize lithium atom in its ground state is x × 10⁻⁸ m. The value of x is:
Q8. The number of atomic orbitals having five radial nodes among 7s, 7p, 6s, 8p and 8d is:
Q9. The magnetic moment of a transition metal compound is 3.87 BM. The metal ion is:
Q10. According to de Broglie hypothesis, the wavelength associated with a moving particle is inversely proportional to:
This chapter explains atomic models, quantum numbers, atomic spectra, wave–particle duality and uncertainty principle. It is a highly scoring chapter in JEE Main with 2–3 questions every year.