1. Presence of fluoride in water greater than permissible level of 1.5 mg/L causes _____.
[A] methemoglobinemia
[B] dental fluorosis
[C] hepatitis
[D] cardiovascular disease
Answer: Option B
2. An inverted siphon is a ______.
[A] derive for preventing crown corrosion of sewer
[B] section of sewer which is dropped below the hydraulic grade line in order to avoid an obstacle
[C] device for preventing overflow from elevated water storage tank
[D] device for distributing septic tank effluent to a soil absorption system
Answer: Option B
3. Symbiosis, the beneficial association between algae and bacteria is used for treatment of waste water in _____ unit.
[A] Rotating biological disc
[B] Oxidation pond
[C] Activated sludge
[D] Anaerobic digestor
Answer: Option B
4. The atmospheric layer closest to the earth surface is ______.
[A] stratosphere
[B] troposphere
[C] thermosphere
[D] mesosphere
Answer: Option B
5. If total hardness and alkalinity of a water sample are 200 mg/l as CaCO3 and 260 mg/l as CaCO3, respectively, what are the values of carbonate hardness and non-carbonate hardness?
[A] Zero and 200 mg/l
[B] Zero and 60 mg/l
[C] 60 mg/l and zero
[D] 200 mg/l and zero
Answer: Option D
Explanation:
CH = min(TH, alkalinity)
= min{200, 260) = 200 mg/l
NCH = TH – alkalinity = 200 – 260 = -60 (negative) i.e. NCH = 0