63) If V is the velocity of flow through a pipe and A is the area of cross section, the rate of flow, Q is calculated using the formula

64) Greasy and other substances which float at the surface of the sewage in a sewage treatment plant is called

65) Maximum Gradient given for 150 mm Drain pipe

66) If A is area of cross section of flow and P is the wetted perimeter, Hydraulic mean depth (R) is

67) For floating impurities in water, density is