Answer
a. The final volume is larger.
b. The final volume is smaller.
c. The final volume is larger.
Work Step by Step
Since the volume is directly related to the temperture, when the temperature increases (at constant pressure and amount of gas), the volume also increases, and vice-versa.
a. The temperature increases, thus, the volume also increases.
b. The temperature decreases when the heater is turned off, thus, the volume also decreases.
c. The temperature increases inside the car, thus, the volume also increases.
