Please help y’all I don’t understand

What does the mass of 0.7891 mol of ferric oxide (fe2o3)

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3

In which of the following phases of matter do molecules have the highest amount of energy? a. liquid b. gel c. solid d. gas