According to diagrams showing elemental abundances in the Milky Way galaxy, which element is the third most abundant?

• A. Nitrogen
• B. Oxygen
• C. Carbon
• D. Iron

Answer: (B)

Verified step by step guidance

1. Understand that elemental abundances in the Milky Way galaxy are typically ranked by the relative number of atoms or mass fraction of each element present in the interstellar medium and stars.
2. Recall that hydrogen is the most abundant element in the galaxy, followed by helium as the second most abundant due to their formation in the Big Bang and stellar processes.
3. Recognize that oxygen is generally considered the third most abundant element in the Milky Way, produced in large quantities by massive stars and supernovae.
4. Note that nitrogen, carbon, and iron are also abundant but rank lower than oxygen in overall abundance.
5. Therefore, based on typical abundance charts and astrophysical data, oxygen is identified as the third most abundant element in the Milky Way galaxy.