Which of these important atomic or molecular species is particularly difficult to detect in the interstellar medium?

Question

Quizplus · Accepted Answer

Molecular hydrogen (H2) is difficult to detect in the interstellar medium because it does not have a permanent electric dipole moment, making its direct observation through radio telescopes challenging. It is usually inferred indirectly through its effects or by observing other molecules.

Which of These Important Atomic or Molecular Species Is Particularly