Question

Pick out the correct statement ?

• A. By decreasing the temperature pure para - hydrogen can be obtained.
• B. By increasing the temperature pure ortho - hydrogen can be obtained.
• C. By decreasing the temperature pure ortho - hydrogen can be obtained.
• D. By increasing the temperature pure para - hydrogen can be obtained.

Answer 1

Answer: (A)

By decreasing the temperature pure para - hydrogen can be obtained.

Ortho hydrogen has spins of both nuclei in same direction. Para hydrogen has spins in opposite direction. At $0^{o}K$, hydrogen contains mainly para hydrogen which is more stable. Pure para hydrogen can be obtained by cooling $H_2$ gas to very low temperature.