I believe the answer is thermal expansion.
To convert from moles to atoms you times the number of mols by Avogadro's number (6.022×10²³)
0.74 × 6.022×10²³ = 4.45628×10²³
Answer: C) The mass stays constant as it changed from a liquid to a gas
Explanation: Mass stays constant, it's never destroyed or created. It follows the law of conservation of mass.
