Question

Ordinary hydrogen at room temperature is a mixture of ____
A.$75\% {\text{ }}o - Hydrogen{\text{ }} + {\text{ }}25\% {\text{ }}p - Hydrogen$
B.$25\% {\text{ }}o - Hydrogen{\text{ }} + {\text{ }}75\% {\text{ }}p - Hydrogen$
C.$50\% {\text{ }}o - Hydrogen{\text{ }} + {\text{ }}50\% {\text{ }}p - Hydrogen$
D.$1\% {\text{ }}o - Hydrogen{\text{ }} + {\text{ }}99\% {\text{ }}p - Hydrogen$

Answer 1

At room temperature the ratio of ortho hydrogen to para hydrogen is $3:1$.It means that the ordinary hydrogen contains three parts or $75\%$ of ortho hydrogen and one part or $25\%$ of para hydrogen .

Complete step by step answer:
According to the question, at room temperature, ordinary hydrogen is in an equilibrium state. At room temperature, it is an equilibrium mixture of $75\%$ ortho hydrogen and $25\%$ para hydrogen. In case of ortho hydrogen, the two protons have spins in the same direction whereas in case of para hydrogen, the protons have spins in the opposite direction.
Therefore, the correct option is (B).

Additional information:
A dihydrogen molecule contains two atoms. In the two molecules the nuclei of both the atoms of dihydrogen are spinning. Depending upon in which direction the spin of the nuclei is taking place, the ordinary hydrogen are of two types:
Ortho hydrogen molecules: Ortho hydrogen molecules are the one in which the spins of both the nuclei of dihydrogen are in the same direction.
Para hydrogen molecules: Para hydrogen molecules are the one in which the spins of both the nuclei of dihydrogen are in the opposite direction
Ordinary dihydrogen is an equilibrium mixture of two types of hydrogens. These two types of hydrogens are orthohydrogen and parahydrogen.
$ortho{\text{ }}hydrogen \rightleftharpoons para{\text{ }}hydrogen$
ortho and para hydrogen gets affected with temperature as follow:
At ${0^ \circ }K$, hydrogen is more stable and contains mainly para hydrogen.
The ratio of ortho hydrogen and para hydrogen is $1:1$ at temperature of liquefaction of air
At the room temperature, the ratio of ortho hydrogen to para hydrogen is $3:1$ .
At very high temperatures, the ratio still can never be more than $3:1$ .

Note:
Ortho and para are two different groups and have very different properties. Also keep in mind that with change in temperature the ratio of the two groups can change.