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2. The elementary reaction, 2A(g)B(g) is run at 990C. The haf life for the reaction is 5.9102s at that temperature. a) What is the rate constant and its unit for the reaction if the initial concentration of A is 0.50M ? (Hint: define the rate law and obtain the half-life equation for this reaction.) (15 p.) b) What will be the concentration of B after 3.6102s if the initial concentration of A is 0.75M and reaction volume is 1.0L ? (15 p.) 3. The equilibrium constant Kcl for reaction-1 is 1.84 at 425C. 2HI(g)H2(g)+I2(g)(reaction-1) The equilibrium constant Kc2 for reaction-2 is 49.7 at 458C. H2(g)+I2(g)2HI(g)(reaction-2) Is reaction-2 endothermic or exothermic? Prove your answer based on the given information. (15 p.)