There are two identical small holes on the opposite sides of a tank containing a liquid. The tank is open at the top. The difference in height between the two holes is h. As the liquid comes out of the two holes, the tank will experience a net horizontal force proportional to

By Toriceli's equation, and p1 = Rate of flow of momentum of water through orifice 1 = ρ.a.V12 = 2ρagh1p2 = Rate of flow of momentum of water through orifice 2 = ρ.a.V22 = 2ρag(h1+h) Resultant force exerted by water on the vessel = (p2 - p1) = 2ρagh. Here 'a' =  area of each hole and ρ = density of water. Hence option (2) is right.