Quiz: Civil Engineering 23 april 2020

Quiz: Civil Engineering (22-april-2020)
Topic: Environmental Engineering

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. The volume (in milliliters) occupied by aerated mixed liquor containing one gram of dry solids after setting for 30 minutes is termed as:
(a) Allowable solids content
(b) Sludge volume index
(c) Liquor index
(d) Chlorination limit

Q2. Activated sludge process is an example of:
(a) Aerobic attached growth process
(b) Anaerobic suspended growth process
(c) Aerobic suspended growth process
(d) Anaerobic attached growth process

Q3. The treatment of water which generally works on biological principles is called:
(a) Primary treatment
(b) Pressure treatment
(c) Desilting treatment
(d) Secondary treatment

Q4. The gases which are generally evolved during anaerobic decomposition of sewage are______.
(a) CO₂ + NH₃ + SO₂ + CH₄
(b) CO₂ + NH₃ + SO₂
(c) CO₂ + NH₃ + H₂S
(d) CO₂ + NH₃ + H₂S + CH₄

Q5. Which of the following processes takes place in trickling filters?
(a) Filtration
(b) Oxidation
(c) Disinfection
(d) Biological action

Q6. In a grit chamber in a sewage treatment plant
(a) Flow velocity 0.15 – 0.3 m/s is kept
(b) Depth 0.9 – 1.2 m is kept
(c) Det time = 1 min
(d) All of the above

Q7. The detention period of a septic tank is of the order of
(a) 2-6 hours
(b) 2-4 hours
(c) 12-36 hours
(d) 4-8 hours

Q8. As per Environmental protection Act, 1986, the noise level in the industrial area during day should not be more than:
(a) 75 dB
(b) 65 dB
(c) 45 dB
(d) 55 dB

Q9. The rain is called as acid rain, when its pH is less than_______
(a) 3
(b) 4.5
(c) 7
(d) 8.5

Q10. Ringelmann’s Scale is used to
(a) Measure CO
(b) measure SO₂
(c) Grade density of smoke
(d) Grade automobile exhaust gas


S1. Ans.(b)
Sol. Sludge volume index → Sludge volume index is defined as volume occupied in ml. by 1 gm. Of solid in the mix liquor when allow to settle for 30 min.
▭(SVI=(Settled Sludge volume (ml))/(MLSS(gm.)))

S2. Ans.(c)
Sol. Activated sludge process is example of aerobic suspended growth system. Sludge generated in secondary sedimentation tank mostly consist of living and active micro-organism, hence it is referred as activated sludge.

S3. Ans.(d)
Sol. Secondary treatment of water is based on biological principles.

S4. Ans.(d)
Sol. the gases which are evolved during anerobic decomposition of sewage are carbon di- oxide (CO2), Ammonia (NH3), Hydrogen sulphide (H2S) and methane (CH4).

S5. Ans.(d)
Sol. Trickling filter is attached aerobic growth system and biological process takes places in trickling filters.

S6. Ans.(d)

S7. Ans.(c)
Sol. The detention period of septic tank is 12 to 36 hours.

S8. Ans.(a)
Sol. as per environmental protection ACT, 1986, the noise level for different zones are following –
Zone                  Day                Night
Industrial           75dB              70dB
Commercial      65dB              55dB
Residential        55dB              45dB
Silence              50dB              40dB

S9. Ans.(b)
Sol. the rain is called as acid rain, when its pH is less than 4.5. then main cause of acid rain is Sulphur oxides (SOx) and Nitrogen oxides (NOx).

S10. Ans.(c)
Sol. Ringelmann’s scale is used to grade density of smoke.


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