To calculate the equilibrium constant K for the given reaction, we can use the expression for the reaction quotient Q and set it equal to K since the reaction is at equilibrium. The expression for Q is given by:Q = [Zn^2+][H2] / [H^+]^2 At equilibrium, Q = K. Therefore,K = [Zn^2+][H2] / [H^+]^2 We are given the concentration of Zn^2+ as 0.25 M, [H^+] as 2.5 10^-3 M, and the pressure of H2 as 0.8 atm. However, we need to convert the pressure of H2 to its concentration using the ideal gas law:PV = nRTWhere P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant 0.0821 L atm/mol K , and T is the temperature in Kelvin. We can rearrange the equation to solve for the concentration n/V of H2:Concentration of H2 = P / RT Plugging in the given values:Concentration of H2 = 0.8 atm / 0.0821 L atm/mol K * 298 K = 0.0325 MNow we can calculate the equilibrium constant K:K = [0.25][0.0325] / [2.5 10^-3]^2 K = 0.008125 / 6.25 10^-6 K = 1300The equilibrium constant for the given reaction is approximately 1300.