The decomposition of hydrogen bromide into hydrogen and iodine is second order reaction.The reaction rate constant is $K=0.08Lmol^{-1}s^{-1}$.How long it take an initial concentration of 0.04M to decrease to half this concentration?

Question

$\begin{array}{1 1}(a)\;300sec&(b)\;315sec\\(c)\;212.5sec&(d)\;312.5sec\end{array}$