No account needed. This session stays in this browser tab; sign in for timed tests, bookmarks and saved performance.
Question 1 · Civil Engineering (SSC JE) · Environmental Engineering The standard BOD test is conducted at
Choose your answer for question 1 A. 27 °C for 3 days B. 20 °C for 5 days C. 37 °C for 5 days D. 20 °C for 10 daysAnswer and explanation Correct answer: B
Standard BOD5 is the oxygen consumed by microorganisms in 5 days at 20 °C.
Question 2 · Civil Engineering (SSC JE) · Environmental Engineering Hardness of water caused by the bicarbonates of calcium and magnesium is called
Choose your answer for question 2 A. temporary hardness B. residual hardness C. total alkalinity D. permanent hardnessAnswer and explanation Correct answer: A
Boiling converts the bicarbonates into insoluble carbonates, which precipitate, so this hardness is called temporary.
Question 3 · Civil Engineering (SSC JE) · Environmental Engineering As per BIS drinking water standards, the acceptable pH range is
Choose your answer for question 3 A. 4.0 to 7.0 B. 8.5 to 10.5 C. 6.5 to 8.5 D. 5.0 to 6.0Answer and explanation Correct answer: C
IS 10500 specifies a pH of 6.5 to 8.5 for drinking water.
Question 4 · Civil Engineering (SSC JE) · Environmental Engineering According to Stokes’ law, the settling velocity of a spherical particle in water is proportional to
Choose your answer for question 4 A. its diameter B. the cube of its diameter C. the square root of its diameter D. the square of its diameterAnswer and explanation Correct answer: D
v = g(ρs − ρ)d² / 18μ, so velocity varies with d².
Question 5 · Civil Engineering (SSC JE) · Environmental Engineering The activated sludge process is a
Choose your answer for question 5 A. biological aerobic treatment process B. chemical precipitation process C. anaerobic digestion process D. physical screening processAnswer and explanation Correct answer: A
Microorganisms in an aerated tank oxidise organic matter. Part of the settled sludge is returned to the tank to keep the biomass high.
Question 6 · Civil Engineering (SSC JE) · Environmental Engineering Which gas is mainly responsible for acid rain?
Choose your answer for question 6 A. Carbon monoxide B. Methane C. Argon D. Sulphur dioxideAnswer and explanation Correct answer: D
SO2 and nitrogen oxides combine with water vapour in the air and form sulphuric and nitric acids.
Question 7 · Civil Engineering (SSC JE) · Environmental Engineering In the arithmetic increase method of population forecasting, the population after n decades is
Choose your answer for question 7 A. P (1 + r)ⁿ B. P − n x̄ C. P + n x̄, where x̄ is the average increase per decade D. P × n x̄Answer and explanation Correct answer: C
The method assumes a constant numerical increase per decade, so Pn = P0 + n x̄.
Question 8 · Civil Engineering (SSC JE) · Environmental Engineering The main gas produced during anaerobic digestion of sewage sludge is
Choose your answer for question 8 A. oxygen B. chlorine C. nitrogen D. methaneAnswer and explanation Correct answer: D
Anaerobic digestion yields biogas of roughly 60 to 70 percent methane and 30 to 40 percent carbon dioxide.
Question 9 · Civil Engineering (SSC JE) · Environmental Engineering A town of 50 000 people has a water demand of 135 litres per capita per day. The average daily demand is
Choose your answer for question 9 A. 0.675 million litres B. 5.0 million litres C. 67.5 million litres D. 6.75 million litresAnswer and explanation Correct answer: D
50 000 × 135 = 6 750 000 litres per day.
Question 10 · Civil Engineering (SSC JE) · Environmental Engineering A sedimentation tank receives 1800 m³/day and has a plan area of 60 m². The surface overflow rate is
Choose your answer for question 10 A. 0.033 m³/m²/day B. 3 m³/m²/day C. 30 m³/m²/day D. 108 m³/m²/dayAnswer and explanation Correct answer: C
Overflow rate = Q/A = 1800 / 60 = 30 m³/m²/day.
Question 11 · Civil Engineering (SSC JE) · Environmental Engineering Beyond the breakpoint of chlorination, additional chlorine added to water appears as
Choose your answer for question 11 A. combined residual chlorine B. chloramines C. chlorides D. free residual chlorineAnswer and explanation Correct answer: D
Up to the breakpoint chlorine is consumed by reactions with ammonia and organic matter. After it, the added chlorine stays as free chlorine.
Question 12 · Civil Engineering (SSC JE) · Environmental Engineering In water treatment, alum reacts with the alkalinity of water to form
Choose your answer for question 12 A. free chlorine B. sodium chloride C. calcium carbonate scale D. aluminium hydroxide flocAnswer and explanation Correct answer: D
Al₂(SO₄)₃ + 3Ca(HCO₃)₂ → 2Al(OH)₃ + 3CaSO₄ + 6CO₂. The gelatinous floc traps suspended particles.
Question 13 · Civil Engineering (SSC JE) · Environmental Engineering The main purpose of a trap in a house drainage system is to
Choose your answer for question 13 A. increase the flow velocity B. trap rainwater for reuse C. filter the sewage D. prevent foul gases from entering the buildingAnswer and explanation Correct answer: D
A water seal in the trap stops sewer gas from coming back through the fixture.
Question 14 · Civil Engineering (SSC JE) · Environmental Engineering The CPCB ambient noise standard for a residential area during the day is
Choose your answer for question 14 A. 45 dB(A) B. 75 dB(A) C. 90 dB(A) D. 55 dB(A)Answer and explanation Correct answer: D
The standard limit is 55 dB(A) in the day and 45 dB(A) at night for residential zones.
Question 15 · Civil Engineering (SSC JE) · Environmental Engineering Composting of solid waste is
Choose your answer for question 15 A. burning of waste at high temperature B. burial of waste in a landfill without air C. aerobic biological decomposition of organic matter into humus D. separation of metals using magnetsAnswer and explanation Correct answer: C
Microorganisms decompose the organic fraction in the presence of oxygen, producing a stable compost.
Question 16 · Civil Engineering (SSC JE) · Environmental Engineering An electrostatic precipitator is used for removing
Choose your answer for question 16 A. particulate matter from flue gases B. ozone from the atmosphere C. carbon monoxide from exhaust D. sulphur dioxide from airAnswer and explanation Correct answer: A
It charges dust particles and collects them on oppositely charged plates. It is not effective on gases.
Question 17 · Civil Engineering (SSC JE) · Environmental Engineering A rooftop of 200 m² receives an annual rainfall of 1000 mm. With a runoff coefficient of 0.7, the volume of water that can be harvested in a year is
Choose your answer for question 17 A. 140 m³ B. 140000 m³ C. 70 m³ D. 200 m³Answer and explanation Correct answer: A
Volume = area × rainfall × C = 200 × 1 × 0.7 = 140 m³.
Question 18 · Civil Engineering (SSC JE) · Environmental Engineering A rapid sand filter system must treat 3000 m³/day at a filtration rate of 4 m³/m²/hour. The total filter area required is
Choose your answer for question 18 A. 62.5 m² B. 31.3 m² C. 500 m² D. 750 m²Answer and explanation Correct answer: B
Area = Q / rate = 3000 / (4 × 24) = 31.3 m².
Question 19 · Civil Engineering (SSC JE) · Environmental Engineering A rooftop of 100 m² receives an annual rainfall of 400 mm. With a runoff coefficient of 0.7, the volume of water that can be harvested in a year is
Choose your answer for question 19 A. 40 m³ B. 112 m³ C. 28000 m³ D. 28 m³Answer and explanation Correct answer: D
Volume = area × rainfall × C = 100 × 0.4 × 0.7 = 28 m³.
Question 20 · Civil Engineering (SSC JE) · Environmental Engineering A rapid sand filter system must treat 3000 m³/day at a filtration rate of 6 m³/m²/hour. The total filter area required is
Choose your answer for question 20 A. 500 m² B. 41.7 m² C. 20.8 m² D. 750 m²Answer and explanation Correct answer: C
Area = Q / rate = 3000 / (6 × 24) = 20.8 m².