Which of the following statements best describes whether an atom of element X can absorb two photons and then emit one photon in the context of endothermic and exothermic reactions?

• A. Yes, if the energy of the emitted photon equals the combined energy of the two absorbed photons, the process is possible.
• B. No, atoms can only absorb and emit photons one at a time due to conservation of energy.
• C. No, because the energy absorbed from two photons must be released as two separate photons during emission.
• D. Yes, but only if the reaction is exothermic and releases more energy than absorbed.

Answer: (A)

Verified step by step guidance

1. Understand the basic principle of photon absorption and emission by atoms: atoms absorb photons to move to higher energy states (excited states) and emit photons when returning to lower energy states (ground or less excited states).
2. Recall that energy conservation is key: the total energy absorbed must equal the total energy emitted, though the number of photons absorbed or emitted can vary depending on the process.
3. Consider whether an atom can absorb two photons sequentially or simultaneously to reach a higher excited state, and then emit a single photon whose energy equals the sum of the two absorbed photons' energies.
4. Analyze the given options in terms of energy conservation and the nature of photon interactions with atoms, noting that atoms are not restricted to absorbing or emitting photons strictly one at a time if the energy balance is maintained.
5. Conclude that the process is possible if the emitted photon's energy equals the combined energy of the two absorbed photons, consistent with conservation of energy and quantum transitions.