Question

How many allotropes of di-hydrogen are known? What is their importance?

Answer 1

Hint: When some chemical elements exist in two or more different forms but in the same physical state, then they are known as allotropes of the elements. This property is known as allotropy or allotropism. They can also show differences in physical and chemical properties.

Complete answer: There are two allotropes of di-hydrogen present in nature. These are Ortho-hydrogen and para hydrogen. The nuclei of both the atoms are spinning. Ortho-hydrogen can be defined as a molecule in which the spins of the nuclei are in the same direction or can be say parallel spin and if the spin of the nuclei is in opposite direction or can be say antiparallel spin, then the molecule is known as para-hydrogen. Para-hydrogen has a lower internal energy than Ortho-hydrogen but para-hydrogen is more stable than Ortho-hydrogen. When the hydrogen is present at room temperature, it is the equilibrium mixture of Ortho-hydrogen and para-hydrogen comprising $75\mathrm{\%}$ Ortho-hydrogen and $25\mathrm{\%}$ parahydrogen. There is also the presence of $99\mathrm{\%}$ para-hydrogen and $1\mathrm{\%}$ Ortho-hydrogen in a sample of ordinary at $25K$.

Note:
The allotropic forms change is caused due to the forces such as light, pressure and temperature. These forces also influence the other structures. Therefore, the stability of many different allotropes relies on specific conditions. One another example of an element which has its allotropes is also there and that is carbon. Diamond and graphite are the two allotropes of carbon.