Final answer:
According to Charles's Law, if the volume of a gas is halved at constant pressure, the absolute temperature of the gas must also be halved.
Step-by-step explanation:
In understanding how the absolute temperature of a gas changes when the volume is halved at constant pressure, one must look at Charles's Law. This law states that at constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature (in kelvins). Therefore, if the volume is halved, the absolute temperature must also be halved.
Mathematically, Charles's Law is stated as VαT, where V is volume and T is temperature. Hence, if the original volume V1 gets reduced to V1/2 while the pressure is constant, the new temperature T2 must adjust so that (V1/2)/T2 = V1/T1, leading to T2 being half of T1 if V1 is halved.