Statement I : A fluid flowing out of a small hole in a vessel apply a backward thrust on the vessel.Statement II :  According to equation of continuity, the product of area and velocity remain constant.

Due to small area of cross-section of the hole, fluid flows out of the vessel with a large speed and thus the fluid possesses a large linear momentum. As no external forces acts on the system, in order to conserve linear momentum, the vessel acquires a velocity in backward direction or in other words a backward thrust results on the vessel.