A waste water sample diluted to 100 times with aeration water had an initial dis

CuriousTab

Home Aptitude

Question
A waste water sample diluted to 100 times with aeration water had an initial dissolved oxygen (DO) of 7.0 mg/l and after 5 days of incubation at 20�C, the DO was zero. The BOD of waste water is :
Options
A. 700 mg/l
B. 100 mg/l
C. cannot be determined
D. 7mg/l

Correct Answer

700 mg/l

4. The masses of two balls are in the ratio of 2 : 1 and their respective velocities are in the ratio of 1 : 2 but in opposite direction before impact. If the coefficient of restitution is , the velocities of separation of the balls will be equal to
Options
A. original velocity in the same direction
B. half the original velocity in the same direction
C. half the original velocity in the opposite direction
D. original velocity in the opposite direction

10. In network of pipes
Options
A. the algebraic sum of discharges around each circuit is zero
B. the algebraic sum of (pressure + datum) head drops around each circuit is zero
C. the elevation of hydraulic grade line is assumed for each junction point
D. elementary circuits are replaced by equivalent pipes

Comments