Question

Which of the following statement(s) is/are true about different forms of hydrogen?

• A. Ortho hydrogen has same spins of two nuclei, i.e. clockwise or anticlockwise
• B. Para hydrogen has different spins of two nuclei
• C. At absolute zero, there is $100\%$ para $H_2$ and at high temperature, there is $75\%$ ortho $H_2$
• D. There are considerable differences between the physical properties of ortho and para forms

Answer 1

Answer: (A), (B), (C), (D)

There are considerable differences between the physical properties of ortho and para forms

The $H_2$ molecule exists in two different forms known as ortho and para hydrogen. In the $H_2$ molecule, the two nuclei may be spinning either in the same direction or in opposite directions.
Ortho hydrogen has same spins of two nuclei, either clockwise or anticlockwise whereas the nuclei of para hydrogen has spins in opposite direction.

The para form has lower energy, and at absolute zero the gas contains $100\%$ of para form. As the temperature is raised, some of the gas changes into the ortho form. At high temperature the gas contains about $75\%$ ortho hydrogen. There are considerable differences between the physical properties such as boiling point, specific heat and thermal conductivities of ortho and para hydrogen, becuase of differences in their internal energy.