For the reaction 2A + B + C→ Products. Rate = K[A][B],and K = 5×10-6 mol-1L1min-1. The initial molar concentrations of A,B,C are respectively 0.1,0.2 and 0.4mol/lit.What is rate after 0.04 mol/lit of reactant  ‘A’ has reacted?

From the stoichiometry of the reaction 0.02 mole/ lit of B is reacted when 0.04 mole/lit of A reacts.Concentration of each reactant after 0.04 mole/ lit of A reacts:[A] = 0.1 - 0.04 = 0.06 mole/lit[B] = 0.2 - 0.02 = 0.18 mole/litRate = K[A][B] = 5×10-6 ×[0.06]×[0.18] = 5.4 ×10-8 mole/lit/minRate is independent of [C] as it is not appearing in rate law.