Structure of Atom – Multiple Choice Questions (MCQs)

1. 37. The number of unpaired electrons in Fe2+ (Atomic No. of Fe = 26) is:

   • A. 4
   • B. 0
   • C. 2
   • D. 5

2. 38. Which of the following atoms has the largest number of neutrons?

   • A. Oxygen-18
   • B. Carbon-12
   • C. Nitrogen-14
   • D. Hydrogen-1

3. 39. The existence of isotopes was first suggested by:

   • A. Frederick Soddy
   • B. Niels Bohr
   • C. Ernest Rutherford
   • D. J.J. Thomson

4. 40. The discovery of the neutron is credited to:

   • A. James Chadwick
   • B. J.J. Thomson
   • C. Ernest Rutherford
   • D. E. Goldstein

5. 41. Which of the following explains the splitting of spectral lines in the presence of a magnetic field?

   • A. Zeeman effect
   • B. Stark effect
   • C. Photoelectric effect
   • D. Compton effect

6. 42. The uncertainty in position and momentum is described by:

   • A. Heisenberg's Uncertainty Principle
   • B. Pauli's Exclusion Principle
   • C. Hund's Rule
   • D. Aufbau Principle

7. 43. The concept of stationary states was a key postulate of:

   • A. Bohr's model of atom
   • B. Rutherford's model of atom
   • C. Thomson's model of atom
   • D. Dalton's atomic theory

8. 44. For an electron, the orbital angular momentum is given by:

   • A. sqrt(l(l+1))h/2π
   • B. mvr
   • C. nh/2π
   • D. l h/2π

9. 45. The radial probability distribution curve for 1s orbital is:

   • A. A single peak
   • B. Two peaks
   • C. Three peaks
   • D. Four peaks

10. 46. The number of degenerate orbitals in a subshell with l=1 is:

    • A. 3
    • B. 1
    • C. 5
    • D. 7

11. 47. The total number of nodes (radial + angular) in an orbital is:

    • A. n-1
    • B. l
    • C. n-l-1
    • D. n+l