521. The difference of pressure between the inside and outside of a liquid drop is________________? A.p = Txr B.p = T/r C. p = T/2r D. p = 2T/r ✅ The correct answer is option D.
522. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is_____________________? A. 50 ppm B. 100 ppm C. 150 ppm D. 200 ppm ✅ The correct answer is option D.
523. Which of the following manometer has highest sensitivity __________________? A. U-tube with water B. inclined U-tube C. U-tube with mercury D. micro-manometer with water ✅ The correct answer is option D.
524. House connections to the laterals is generally made by___________________? A. R.C.C. B. P.C.C. C. Cast iron D. Glazed stonewares ✅ The correct answer is option D.
525. In sewers designed with self cleansing velocity________________? A. The bottom is silted B. The bottom is scoured C. Both silting and scouring occur at the bottom D. Neither silting nor scouring occurs at the bottom ✅ The correct answer is option D.
526. In case of sewer lines_________________? A. Water test is carried out to check water tightness of the joints B. Test for straightness is carried out with the help of a lamp and mirror C. Obstruction test is carried out with the help of smooth ball of diameter 13 mm D. All the above ✅ The correct answer is option D.
527. The temperature affects the________________? A. Biological activity of bacteria in sewage B. Solubility of gases in sewage C. Viscosity of sewage D. All the above ✅ The correct answer is option D.
528. The rise or depression of liquid in a tube due to surface tension wim increase in size of tube will_______________? A. increase B. remain unaffected C. may increase or decrease depending on the characteristics of liquid D. decrease ✅ The correct answer is option D.
529. Cavitation is caused by___________________? A. high velocity B. high pressure C. weak material D. low pressure ✅ The correct answer is option D.
530. Mercury is often used in barometer because _________________? A. it is the best liquid B. the height of barometer will be less C. its vapour pressure is so low that it may be neglected D. both B. and C. ✅ The correct answer is option D.