64) The discharge through an external mouthpiece is given by (where a = Cross-sectional area of the mouthpiece, and H = Height of liquid above the mouthpiece)

65) The loss of pressure head in case of laminar flow is proportional to

66) The flow of water through the hole in the bottom of a wash basin is an example of

67) A glass tube of smaller diameter is used while performing an experiment for the capillary rise of water because

68) The viscosity of a liquid is due to cohesion of its particles.