Which of the following statements concerning the quantum numbers is correct (i) The Angular quantum number determines the three-dimensional shape of the orbital. (ii) The Principal quantum number determines the orientation and energy of the orbital. (iii) The Magnetic quantum number determines the size of the orbital. (iv) Spin quantum number of an electron determines the orientation of the spin of the electron relative to the chosen axis.?

Option 2 : i and iv

The correct answer is Option 2, i.e i and iv.

• An atom consists of many orbitals which are distinguished from each other based on their shape, size and orientation in space.
• Thus Quantum number are those numbers that designate and distinguish various atomic orbitals and electrons present in an atom.
• There are four types of quantum number:
• Angular quantum number determines the three-dimensional shape of the orbital quantum number.
  • Denoted by the symbol ‘l’ is also known as orbital angular momentum or subsidiary quantum number.
  • It defines the three-dimensional shape of the orbital.
• Principal quantum number
  • ​Denoted by the symbol ‘n’.
  • Determines the size and to a large extent the energy of the orbital. Hence, statement (ii) is NOT correct.
• Magnetic orbital quantum number
  • ​Denoted by the symbol ‘ml’.
  • Gives information about the spatial orientation of the orbital concerning standard set of co-ordinate axis. Hence, statement (iii) is NOT correct.
• Electron Spin quantum number
  • ​Denoted by the symbol (ms) refers to the orientation of the spin of the electron.