Discussion
For ortho-hydrogen, the nuclear wavefunction and the rotational quantum number, respectively, are
Answer: B
For ortho-hydrogen the nuclear wavefunction is symmetric and the rotational quantum number is odd.
Protons are fermions, so the total wavefunction of H2 must change sign when the two nuclei are exchanged. In ortho-hydrogen the nuclear spins are parallel (total nuclear spin I = 1), and the three spin functions of a triplet are symmetric under exchange. The rotational part must then be antisymmetric, and rotational functions are antisymmetric under exchange only for odd J (1, 3, 5, ...).
Para-hydrogen is the opposite case: antisymmetric nuclear spin (I = 0) paired with even J. 'Antisymmetric and even' therefore describes para, not ortho, and the two mixed combinations (symmetric with even, antisymmetric with odd) would give a total wavefunction that is symmetric under exchange, which the Pauli principle forbids.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development