A sealed flask containing a small amount of liquid is weighed. All the liquid evaporates inside the flask. The flask is weighed again after returning to its original temperature. Which statement explains the result?
The mass decreases because the gas particles have less mass.
The mass is unchanged because no particles leave the flask.
The mass increases because the particles occupy more space.
The mass is unchanged because the particles stop moving.
87 exam-style questions on Edexcel GCSE Physics 14.1 Density and states of matter, covering 14.1.1 Kinetic theory and states of matter, 14.1.2 Density, and 14.1.3 Density and changes of state. Each one has a worked solution and a mark scheme showing where the marks go.