The reaction quotient Q is calculated using the concentrations of the reactants and products raised to the power of their stoichiometric coefficients in the balanced chemical equation. For the given reaction:2NO g + O2 g 2NO2 g The formula for Q is:Q = [NO2]^2 / [NO]^2 * [O2] Given the concentrations:[NO] = 0.50 M[O2] = 0.25 M[NO2] = 0.75 MPlug the values into the formula:Q = 0.75^2 / 0.50^2 * 0.25 Q = 0.5625 / 0.25 * 0.25 Q = 0.5625 / 0.0625Q = 9The reaction quotient Q for the given reaction at 298K is 9.