Question

which of these actions increases enthalpy in the air molecules of the earths atmosphere?
a. the air being heated by the sun
b. trees being planted in the rain forests
c. carbon dioxide being taken in by plants during photosynthesis
d. people breathing in oxygen

Explanation:

Enthalpy is a measure of total heat in a system. Heating air molecules directly adds thermal energy, increasing their enthalpy. The other options do not add heat to atmospheric air molecules: tree planting and CO₂ uptake by plants involve carbon cycling, and oxygen intake by breathing is a biological gas exchange that does not increase air molecule enthalpy.

Answer:

A. The air being heated by the sun