We have a container of a hot ideal monatomic gas. The volume of the container is 25 liters. The temperature of the gas is 221 ◦C, and its pressure is 0.858 × 105 Pa. We allow the gas to cool down to room temperature, which at the time is 21◦C. We do not allow the volume of the gas to change. 

(a) Find the final pressure (Pa) of the gas. 

(b) Find the amount of heat (J) that passed from the gas to its surroundings as it cooled. Give a positive value. 

(c) Find the change of internal energy (J) of the gas. Be sure to include the correct sign on the answer