The mass of the sample collected from the gases of the car exhaust is 1.22 g. The volume of the sample at a temperature of 24 degree Celsius and at a pressure of 1 atm. is equal to 991 mL. The temperature in Kelvin is equal to 297 K.
To determine the number of moles of gas collected the Gas Law is used which gives the relation between pressure P, volume V, the number of moles of the gas n, the temperature T as PV = n*R*T where R is a constant equal to 82.057 cm^3 atm/ K*mol
Substituting the values given: 1*991 = n*82.057*297
=> n = 991/ (82.057*297)
=> 0.0407 moles
The amount of gas present in the sample is equal to 0.0407 moles.