A certain mass of gas occupied 450cm cube at 25°c.At what temperature will it have it's volume reduced half
25 + 273 = 298 degrees Kelvin
P V = n R T
n and R are constant
You do not mention P, so I guess maybe the pressure is constant?
V/T = n R/P = constant
so
V1/T1 = V2/T2
T2 = (V2/V1) T1
T2 = .5 T1 = 298/2 = 149 K
-273 + 149 = - 124 C
That is wicked chilly.