Answer:
Volcanologists use many different kinds of tools including instruments that detect and record earthquakes (seismometers and seimographs), instruments that measure ground deformation (EDM, Leveling, GPS, tilt), instruments that detect and measure volcanic gases (COSPEC), instruments that determine how much lava is moving underground (VLF, EM-31), video and still cameras, infrared cameras, satellite imagers, webcams, etc!
Explanation:
I HOPE IT HELPED
Don't really know if this is what your asking but P1/T1= P2/T2 should show how the pressure varies with temperature (V is left out because it's constant since the gas is trapped in an aerosol can). As the temperature rises the pressure rises and if it gets too high then the can explodes, which is why it should be stored in a cool place. There's also PV=nRT might be kind of hard to find moles (n) though.
Answer: There are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.
Explanation:
Given: 
= 2.25 L, 
= 9.0 mol
= 1.85 L, 
= ?
Formula used to calculate the moles of helium are as follows.
Substitute the values into above formula as follows.
Thus, we can conclude that there are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.
1 atom Mg, 2 atoms O and 2 atoms H.
1 + 2 + 2 = 5, so correct answer is C
