Which of the following is true about hygroscopic substances
a. they have low vapor pressures
b. they remove moisture from the air
c. they can be used as drying agents
d. all of the above

B is fasho the answer thank me later, It's not C because it can be used as a drying agent but not all hygroscopic substances are Drying agents and It also can be A

Answer : The mole fraction of methane and propane is, 0.742 and 0.26

Explanation :

First we have to calculate the moles of mixture by using ideal gas equation.

PV = nRT

where,

P = pressure of the mixture = 1.00 atm

V = Volume of the mixture = 5.04 L

T = Temperature of the mixture =

R = Gas constant =

n = number of moles of mixture = ?

Putting values in above equation, we get:

Let the number of moles of methane be 'x' moles and that of propane be 'y' moles

So,      .....(1)

The chemical equation for the combustion of methane follows:

By Stoichiometry of the reaction:

1 mole of methane produces 1 mole of carbon dioxide

So, 'x' moles of methane will produce = moles of carbon dioxide

The chemical equation for the combustion of propane follows:

By Stoichiometry of the reaction:

1 mole of propane produces 3 mole of carbon dioxide

So, 'y' moles of propane will produce = moles of carbon dioxide

Now we have to calculate the mass of carbon dioxide.

Total moles of carbon dioxide = (x + 3y)

Mass of carbon dioxide = (Total moles) × (Molar mass of carbon dioxide)

Molar mass of carbon dioxide = 44 g/mol

Mass of carbon dioxide =

As we are given:

Mass of carbon dioxide = 15.0 g

So,     .....(2)

Putting value of 'x' from equation 1, in equation 2, we get:

Evaluating value of 'x' from equation 1, we get:

Mole fraction of a substance is given by:

For Methane:

Moles of methane = 0.167 moles

Total moles = 0.225

Putting values in above equation, we get:

For Propane:

Moles of propane = 0.058 moles

Total moles = 0.225

Putting values in above equation, we get:

Hence, the mole fraction of methane and propane is, 0.742 and 0.26