Nitrogen dioxide, $\text{NO}_2$, is a dark brown gas that breaks down according to the equation $2\text{NO}_2(g) \rightleftharpoons 2\text{NO}(g) + \text{O}_2(g)$. The diagram shows a glass flask holding a mixture of these three gases. The mixture is pale brown. More oxygen is pushed into the flask. Which colour change is observed in the mixture?
- AIt becomes a darker brown.
- BIt becomes a paler brown.
- CIt turns colourless.
- DThere is no change.