Which of the following metals burns in the vapor phase during combustion analysis?

• A. Copper
• B. Magnesium
• C. Sodium
• D. Iron

Answer: (C)

Verified step by step guidance

1. Understand the concept of combustion analysis: it involves burning a substance to analyze the products formed, often to determine elemental composition.
2. Recall that metals can burn either in the solid phase or in the vapor phase depending on their physical and chemical properties, such as volatility and reactivity.
3. Consider the metals listed: Copper, Magnesium, Sodium, and Iron. Among these, Sodium is known to have a relatively low boiling point and high reactivity, which allows it to vaporize and burn in the vapor phase during combustion.
4. In contrast, metals like Copper, Magnesium, and Iron typically burn in the solid phase because they have higher melting and boiling points and do not vaporize easily under combustion conditions.
5. Therefore, identify Sodium as the metal that burns in the vapor phase during combustion analysis due to its ability to vaporize and react in the gas phase.