Consider the following standard reversible reactions: I. N ₂( g ) + 3 H ₂( g ) 2 NH ₃( g ) II. PCl ₅( g ) PCl ₃( g ) + Cl ₂( g ) III. N ₂( g ) + O ₂( g ) 2 NO ( g ) IV. 2 O ₃( g ) 3 O ₂( g ) V. CaCO ₃( s ) CaO ( s ) + CO ₂( g ) VI. 2 SO ₂( g ) + O ₂( g ) 2 SO ₃( g ) The number of reactions from the above list where the equilibrium shifts in the forward direction upon BOTH increasing the temperature and decreasing the

Step-by-step solution

According to Le Chatelier's principle: 1. Increasing the temperature shifts the equilibrium in the endothermic direction ( H > 0 ). 2. Decreasing the pressure shifts the equilibrium in the direction that produces more moles of gas ( n_g > 0 ). We must identify the reactions that are both endothermic and have n_g > 0 . Let us analyse the given reactions: I. Haber process: Exothermic, n_g = 2 - 4 = -2 II. Decomposition of PCl ₅ : Endothermic, n_g = 2 - 1 = +1 III. Formation of NO : Endothermic, n_g = 2 - 2 = 0 IV. De