The formation of NH3(g) follows Le-Chatelier's principle. At equilibrium, N2(g)+3H2(g)⇌2NH3(g) The above reaction proceed in forward direction with increase in pressure resulting in increase in yield of NH3. But as product NH3 is in gaseous state and is liquified. So, with decrease in temperature, there will be increase in yield of ammonia. So, its given T1<T2. Therefore, yield of NH3 will be more at T1 than T2. The graph in option (a) represents correct yield of NH3.