The pressure of a gas in a container is 152 mm Hg. This is equivalent to ____. 0.2 atm 2 atm 0.3 atm 0.4 atm 2. If a liquid is sealed in a container and kept at constant temperature, how does its vapor pressure change over time? It continues to steadily increase. It increases at first, then remains constant. It increases at first, then decreases. It continues to steadily decrease. 3. Compared to the melting points of ionic compounds, the melting points of molecular solids tend to be ____. similar unpredictable lower higher 4. The smallest group of particles in a crystal that retains the shape of the crystal is called the ____. cube unit cell cage crystal lattice