Kassie is 7. She completes exactly two of the 15 arithmetic problems she has been assigned for homework before starting a video game. Kassie's behavior BEST exemplifies:

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water