Determine the mole fractions and partial pressures of CO2, CH4, and He in a sample of gas that contains 1.20 moles of CO2, 1.79 moles of CH4, and 3.71 moles of He, and in which the total pressure is 5.78 atm.

Answer :  The mole fraction and partial pressure of and gases are, 0.267, 0.179, 0.554 and 1.54, 1.03 and 3.20 atm respectively.

Explanation : Given,

Moles of = 1.79 mole

Moles of = 1.20 mole

Moles of = 3.71 mole

Now we have to calculate the mole fraction of and gases.

and,

and,

Thus, the mole fraction of and gases are, 0.267, 0.179 and 0.554 respectively.

Now we have to calculate the partial pressure of and gases.

According to the Raoult's law,

where,

= partial pressure of gas

= total pressure of gas  = 5.78 atm

= mole fraction of gas

and,

and,

Thus, the partial pressure of and gases are, 1.54, 1.03 and 3.20 atm respectively.

the answer is a and have a great day

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)