The reaction sequence provided is as follows:

C2H5OH (ethanol) undergoes dehydration to form C2H4 (ethylene) by losing a water molecule.

C2H4 (ethylene) reacts with HCl to form C2H5Cl (chloroethane) by adding a chlorine molecule.

C2H5Cl (chloroethane) undergoes hydrolysis to form C2H5OH (ethanol) by breaking the C-Cl bond and replacing it with an -OH group.

C2H5OH (ethanol) reacts with NaOH (sodium hydroxide) to form C2H5ONa (sodium ethoxide) by replacing an -OH group with a sodium ion.