Calculate the partial pressure of NO2 Calculate the partial pressure of $\ce{NO2}$.

$$p_{\ce{N2}}/p_{\ce{O2}}=5$$

$$\ce{N2(g) + O2(g) &lt;=&gt; 2NO(g)}$$

Let’s assume $K=0.1$

$$K= \frac{p_{\ce{NO}}^2}{p_{\ce{O2}}\cdot p_{\ce{N2}}}$$

$$K= \frac{p_{\ce{NO}}^2}{p_{\ce{O2}}\cdot p_{\ce{O2}}\cdot5}$$

But how do I proceed?
Ok.
Now you have 3 variables and 2 equations.
To solve the problem you need 3 equations.

Third equation you'll get from the partial pressure law: 


  The total pressure of an ideal gas mixture is the sum of the partial pressures of each individual gas in the mixture.


Tip: suppose total pressure is 1.