As pressure decreases, density: does what increases, decreases, or stays the same

As pressure decreases, density decreases

Explanation:

Pressure applied  on a given system is essentially the force acting per units area of that system. Volume occupied by  a system is inversely proportional to the pressure.  As pressure is decreased the volume tends to increase.

Density is another property of matter which is inversely related to the volume.

i.e.

Therefore, when mass of the system is constant, decreasing the pressure will increase the volume which would in turn decrease the density.

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm