(N/A) $(i)$ Bernoulli's theorem is derived based on the principle of conservation of energy,assuming that no energy is lost due to friction. However,in reality,when fluids flow,energy is lost due to internal friction (viscosity). Viscous forces acting between different layers of the fluid result in a loss of energy.
$(ii)$ The theorem assumes the fluid is incompressible. In practice,the elastic energy of the fluid is not taken into consideration,which limits the theorem's applicability to compressible fluids.
$(iii)$ The theorem assumes steady,streamline flow. It does not account for turbulent flow,where velocity and pressure at a point change randomly with time.