Explanation:

The relationship between the pressure, volume, temperature and number of moles of a gas is described by the Ideal Gas Law, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature in Kelvin.

Let's first find the number of moles of the ammonia sample using the initial conditions:

V = 0.250 L

P = 0.850 atm

T = 27°C = 300.15 K

R = 0.08206 L atm K-1 mol-1

n = (PV) / (RT) = (0.850 atm * 0.250 L) / (0.08206 L atm K-1 mol-1 * 300.15 K) = 0.0078 moles

Now that we know the number of moles of ammonia, we can find its pressure when the volume changes to 0.538 L and temperature changes to 0°C = 273.15 K:

V = 0.538 L

n = 0.0078 moles

T = 273.15 K

R = 0.08206 L atm K-1 mol-1

P = (nRT) / V = (0.0078 moles * 0.08206 L atm K-1 mol-1 * 273.15 K) / 0.538 L = 0.535 atm

So, the pressure of the ammonia sample becomes 0.535 atm when the volume becomes 0.538 L and temperature changes to 0°C. I hope this has answered your question. Please give a heart if it has. Thank you!!