<u>Answer:</u> The mass percent of nitrogen gas and hydrogen gas is 91.41 % and 8.59 % respectively.
<u>Explanation:</u>
To calculate the number of moles, we use the equation given by ideal gas equation:
PV = nRT
where,
P = Pressure of the gaseous mixture = 1.00 atm
V = Volume of the gaseous mixture = 24.62 L
n = number of moles of the gaseous mixture = ?
R = Gas constant = 
T = Temperature of the gaseous mixture = 300 K
Putting values in above equation, we get:

We are given:
Total mass of the mixture = 13.22 grams
Let the mass of nitrogen gas be 'x' grams and that of hydrogen gas be '(13.22 - x)' grams
To calculate the number of moles, we use the equation:

<u>For nitrogen gas:</u>
Molar mass of nitrogen gas = 28 g/mol

<u>For hydrogen gas:</u>
Molar mass of hydrogen gas = 2 g/mol

Equating the moles of the individual gases to the moles of mixture:

To calculate the mass percentage of substance in mixture we use the equation:

Mass of the mixture = 13.22 g
Mass of nitrogen gas = x = 12.084 g
Putting values in above equation, we get:

Mass of hydrogen gas = (13.22 - x) = (13.22 - 12.084) g = 1.136 g
Putting values in above equation, we get:

Hence, the mass percent of nitrogen gas and hydrogen gas is 91.41 % and 8.59 % respectively.