Chemical reaction engineering question

$2)$ The irreversible, elementary gas$-$phase reaction A $+$ B $->$ C $+$ D takes place in an isothermal$($T $=400$K$)$ packed bed reactor with pressure drop. Calculate the conversion exiting the reactor.

CA$0=1$ mol$/$dm$3,$ CB$0=2$ mol$/$dm$3,$

u o $=5$ dm$3/$min$,$ kA$(400$K$)=0\mathrm{.}25$dm$6/$mol$$min$,\backslash$alpha $=0\mathrm{.}03$ kg$1,$ W $=30$ kg

b$)$ Repeat for the case in which there is no pressure drop $(\backslash$alpha $=0).$

c$)$ Explain any difference $($or lack thereof$)$ between the two answers above