Gaseous mixture contains 56 g of N₂, 44 g of CO₂ and 16g of CH₄. The total pressure of mixture is 720 mm of Hg . The partial pressure of methane is

First of all we have to calculate the number of moles.
Number of moles of N₂ $= \frac{56}{28} = 2$
Number of moles of CO₂ = $\frac{44}{44} = 1$
Number of moles of CH₄ = $\frac{16}{16 } = 1$
$\therefore$ Total number of moles = 2+1+1 = 4
$\therefore$ mole fraction of CH₄ = $\frac{1}{4}$
$\therefore \text{ partial pressure of }{\mathrm{CH}}_4$
$\begin{array}{l}=\text{ mole fraction of }{\mathrm{CH}}_4\times \text{ total pressure }\\ =\frac{1}{4}\times 720=180\mathrm{atm}\end{array}$