The rate of the first-order reaction X→products is 7.5×10−4 mol L−1 min−1. What will be the value of rate constant when the concentration of X is 0.5 mol L-1?

Rate of reaction =7.5×10−4 mol L−1 min−1                         =7.5×10−460mol L−1 s−1                       =1.25×10−5 mol L−1 sec−1Rate of reaction = k [concentration of reactant X] or k=1.25×10−50.5=2.5×10−5s−1