The Rate Constant for a Particular Second- Order Reaction Is

The rate constant for a particular second- order reaction is 0.47 M^{- 1}s^{- 1}. If the initial concentration of reactant is 0.25 mol/L, it takes s for the concentration to decrease to 0.13 mol/L.

A) 1.7
B) 1.4
C) 7.9
D) 0.13
E) 3.7