A solution of A is mixed with equal volume of a solution of B containing the same number of moles,for reaction $A+B\rightarrow C$.At the end of 1 hour,A is 75% reacted.How much of A will be left unreacted at the end of 2hours if the reaction is first order in A & zero order in B.

Question

$\begin{array}{1 1}(a)\;14.23\%&(b)\;0\%\\(c)\;6.25\%&(d)\;50\%\end{array}$