Answer: 584 mm Hg
Explanation:
According to Raoult's law, the partial pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the total pressure.
[tex]p_1=x_1P[/tex]
where, x = mole fraction
[tex]P[/tex] = total pressure = 749 mmHg
[tex]x_{N_2}=\frac{\text {moles of }N_2}{\text {total moles}}=\frac{78}{100}=0.78[/tex]
Putting in the values we get:
[tex]p_1=0.78\times 749mmHg=584mmHg[/tex]
The partial pressure of nitrogen will be 584 mmHg