The reaction sequence begins with the reaction of isopropanol with phosphorus tribromide to yield isopropyl bromide. This is followed by reaction with Magnesium in ether solution giving a grignard reagent, isopropyl magnesium bromide. This is now attacked by oxirane and the epoxide ring opens, hydrolysis of the product, followed by oxidation using pyridinium chlorochromate (PCC) yields the final product- (CH3)2CHCH2CHO
The detailed reaction mechanism is attached to this answer.
Chemical equilibrium is reached by the forward reaction rate equaling the reverse reaction rate. If the reaction is not reversible, this could not occur.