A chemist prepares a solution by dissolving 5.00g of NaCl in 95.0g of water, giving an initial mass percent of NaCl equal to 5.00%. The beaker is left uncovered overnight, and some water evaporates while no NaCl is lost. Which statement best describes the mass percent of NaCl after evaporation?
(a) It becomes less than 5.00% because a portion of the NaCl precipitates out of solution as water evaporates.
(b) It remains exactly 5.00% because neither the mass of NaCl nor the mass of water has changed appreciably.
(c) It becomes greater than 5.00% because the total mass decreases while the mass of NaCl remains constant.
(d) It cannot be determined without knowing the exact mass of water lost during evaporation.