Question

Ratio of ortho and para hydrogen in ordinary hydrogen is?
A. 1:3
B. 2:3
C. 3:1
D. None of the above

Answer 1

Hint: We should know that at room temperature, ortho hydrogen is more stable compared to para hydrogen. So, the ratio would be greater than one. Now try to answer this accordingly.

Complete step by step answer:
Molecular hydrogen can exist in two different nuclear spin configurations, named "ortho" and "para". The difference between these two configurations is the symmetry of the nuclear wavefunction. The effect of this difference can be seen in the rotational energy of the molecule
The hydrogen atom in which the nuclear spin and the spin of the orbits are in the different directions is para hydrogen.
The hydrogen atom in which the nuclear spin and the spin of the orbits are in the same direction is ortho hydrogen.
We should know that the amount of ortho and para hydrogen varies with temperature as-
1. At 0 K, hydrogen contains mainly para-hydrogen which is more stable.
2. At the temperature of liquefaction of air, the ratio of ortho and para hydrogen is 1:1.
3. At room temperature, the ratio of ortho to para-hydrogen is 3:1.
4. Even at very high temperatures, the ratio of ortho to para-hydrogen can never be more than 3:1.
Therefore, we can conclude that the correct answer to this question is option C.

Note: We can also say that it has been possible to get pure para-hydrogen by cooling ordinary hydrogen gas to a very low temperature (close to 20 K) but it is never possible to get a sample of hydrogen-containing more than 75% of ortho hydrogen.