Question

Which of the following molecules is likely to be the most common in interstellar space?

A) OH, hydroxyl
B) H2, molecular hydrogen
C) CO, carbon monoxide
D) H2O, water

Answer 1

H2, molecular hydrogen, is the molecule most commonly found in interstellar space, especially in giant molecular clouds. Carbon monoxide (CO) is also prevalent and is used by astronomers to trace molecular hydrogen.

Step-by-step explanation:

The molecule most commonly found in interstellar space is H2, molecular hydrogen. While interstellar space is

known for its harsh conditions with ultraviolet light from stars capable of breaking molecules apart, regions known as giant molecular clouds are shielded from this radiation, allowing molecules to form and survive. In these giant molecular clouds, molecular hydrogen is particularly abundant, forming the primary component of interstellar hydrogen. However, it is difficult to detect directly because it does not emit strongly at radio wavelengths in the cold environments of these clouds. Instead, astronomers often detect carbon monoxide (CO), which is also prevalent in these clouds and serves as a tracer for molecular hydrogen.