Nitrogen dioxide, $\text{NO}_2$, is a brown gas. Dinitrogen tetroxide, $\text{N}_2\text{O}_4$, is a colourless gas. In a closed vessel, an equilibrium is set up between $\text{NO}_2$ and $\text{N}_2\text{O}_4$. $2\text{NO}_2(g) \rightleftharpoons \text{N}_2\text{O}_4(g) \qquad \Delta H = -57\ \text{kJ mol}^{-1}$ Which row gives the effect of altering the conditions on the colour of an equilibrium mixture of $\text{NO}_2$ and $\text{N}_2\text{O}_4$?