Acetaldehyde decomposes in an ideal reactor in piston flow at $400$C$$ and $1$ atmosphere according to the reaction

CH$3$CHO $->$ CH$4+$CO

The reaction is second order $($k$=0\mathrm{.}3$ l$/$mol$.$sec$).$ What is the volume needed in the reactor to obtain $40\%$ conversion when the molar flow at the inlet is $1200$ mol$/$h of acetaldehyde.