A hydrogen gas volume thermometer has a volume of 100.0 cm3

For hydrogen, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature.

Initially:

P1 = P, V1 = 100 cm3, n1 = n, T1 = 0 + 273 = 273 K

PV1 = nRT1

Finally: P2 = P, V2 = 87.2 cm3, n2 = n, T2 = ?

PV2 = nRT2

Note that P, n, and R are the same. Therefore, the equations may be rewritten:

P/nR = T1/V1 = T2/V2 and T2 = V2T1/V1

Plugging in the values we know:

T2 = 87.2 cm3 x 273 K / 100.0 cm3

T2 = 238 K

Answer : 238 K (which could also be written as - 35°C)