<p>Explanation worth2try:</p>
<p>1A(g) + 1B(g) ->/<- 1C(g)</p>
<p>There are 2 moles of gas on the left side, and 1 mole of gas on the right side. When gases are compressed, they become more pressurized, so they want to relieve that pressure. In order to do this, the 2 moles of reactants can be significantly decreased to 1 mole, thereby relieving the pressure.</p>