 Original gas sample. |  Increase V. Expand 1.0 mol of gas molecules at 273 K until the pressure is 0.5 atm. |  Increase T. Heat 1.0 mol of gas molecules at 1.0 atm to a temperature of 546 K. |  Increase n. Add 1.0 mol of gas molecules to the container at STP, to arrive at 2.0 total moles. |