Choose the correct option for the total pressure (in atm.) in a mixture of 4 g O₂ and 2 g H₂ confined in a total volume of one litre at 0⁰C is : [Given R=0.082 L atm mol−1K−1, T=273 K]

The correct option is 25.18.

To find the total pressure of the gaseous mixture, we can use Dalton's Law of Partial Pressures and the Ideal Gas Law:
$PV=n_{\text{total}}RT$
where:
• $P$ is the total pressure,
• $V$ is the volume of the container ($1\text{L}$),
• $n_{\text{total}}$ is the total number of moles of gas,
• $R$ is the universal gas constant ($0.082\text{L atm}{\text{mol}}^{-1}{\text{K}}^{-1}$),
• $T$ is the temperature in Kelvin ($273\text{K}$).

First, we calculate the number of moles of each gas in the mixture.
The molar mass of Oxygen gas (${\text{O}}_2$) is $32\text{g/mol}$.
The number of moles of Oxygen ($n_{{\text{O}}_2}$) is:
$n_{{\text{O}}_2}=\frac{4\text{g}}{32\text{g/mol}}=0.125\text{mol}$

The molar mass of Hydrogen gas (${\text{H}}_2$) is $2\text{g/mol}$.
The number of moles of Hydrogen ($n_{{\text{H}}_2}$) is:
$n_{{\text{H}}_2}=\frac{2\text{g}}{2\text{g/mol}}=1\text{mol}$

Next, we calculate the total number of moles ($n_{\text{total}}$) in the mixture:
$n_{\text{total}}=n_{{\text{O}}_2}+n_{{\text{H}}_2}=0.125+1=1.125\text{mol}$

Now, we apply the Ideal Gas Equation to solve for the total pressure ($P$):
$P=\frac{n_{\text{total}}RT}{V}$
Substituting the given values:
$P=\frac{1.125\times 0.082\times 273}{1}$
$P=25.2165\text{atm}$

Comparing this with the options, the value closest to our calculation is 25.18.
Thus, the total pressure of the mixture is 25.18 atm.