At high temperatures, nitrogen directly combines with: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: According to Le Chatelier's principle, an increase in temperature shifts the equilibrium in the endothermic direction. Since the mixture becomes darker at high temperatures, the concentration of the darker species must increase. Step 2: NO2 is a reddish-brown gas, whereas N2O4 is a colorless gas. Since the color darkens at higher temperatures, the dimerization reaction 2NO2 <=> N2O4 must be exothermic. Step 3: This confirms that the reaction is exothermic and NO2 is darker in color than N2O4, which corresponds to option (a).