Physical changes and changes of state Original Scenario-Based Download PDF

Questions

1. 1.

   In an experimental botanical greenhouse, a botanist uses a block of solid dry ice that sublimes directly into gaseous carbon dioxide to enrich the air, while adjacent mist nozzles spray liquid water that condenses on cold glass panels and freezes into frost. Neither process produces any new chemical substances or breaks the internal bonds of the molecules involved. Which statement correctly identifies and compares these transformations?

   • A) The sublimation of dry ice is a chemical change because a phase change from solid to gas alters the molecular formula, whereas the freezing of water is purely physical.
   • B) Both processes are physical changes because only the arrangement and kinetic energy of the molecules change, leaving their chemical identities unaltered.
   • C) The freezing of water into frost represents a chemical synthesis reaction because a new solid lattice forms, whereas the sublimation of dry ice is a physical change.
   • D) Both processes are chemical changes because energy is transferred, which permanently alters the characteristic intrinsic properties of the substances.