#### Answer

Molar mass = 70.75 g/mol

#### Work Step by Step

The mass of a sample of gas is 827 mg. Its volume is 0.270 L at a temperature of 88 °C and a pressure
of 975 mmHg
m = 827 mg = 0.827 g
V = 0.270 L
T = 88 + 273.15 = 361.15 K
P = 975 mmHg = 1.283 (760 mmHg = 1 atm)
Using n = PV/RT
n = 1.283 x 0.270 / 0.08206 x 361.15
n = 0.0117
M = m/n
M = 0.827/ 0.0117
M = 70.75