Question

Ordinary hydrogen at room temperature is a mixture of:

• A. $75\%$ ortho-hydrogen $+25\%$ para-hydrogen
• B. $25\%$ ortho-hydrogen $+75\%$ para-hydrogen
• C. $50\%$ ortho-hydrogen $+50\%$ para-hydrogen
• D. $1\%$ ortho-hydrogen $+99\%$ para-hydrogen

Answer 1

The correct option is A $75\%$ ortho-hydrogen $+25\%$ para-hydrogen

At room temperature, ordinary hydrogen is an equilibrium mixture of $75\%$ ortho-hydrogen and $25\%$ para-hydrogen. In ortho-hydrogen, the spins of two protons are in the same direction whereas in para hydrogen, the spins of two protons are in the opposite direction.