Question

Which of the following is true about different forms of hydrogen?

• A. Ortho hydrogen has same spins of two nuclei, clockwise or anticlockwise.
• B. Para hydrogen has different spins of two nuclei.
• C. At absolute zero, there is $100\%$ para form and at high temperature, there is $75\%$ ortho form.
• D. All of the above statements are correct.

Answer 1

The correct option is D All of the above statements are correct.

Molecular hydrogen occurs in two isomeric forms: one with its two proton spins aligned parallel (ortho hydrogen) and the other with its two proton spins aligned antiparallel (para hydrogen).

At room temperature and thermal equilibrium, hydrogen consists of approximately $75\%$ ortho hydrogen and $25\%$ para hydrogen.

The para form dominates at low temperatures $($approx. $99.8\%$ at $20$ K$)$.