Environmental Engineering (General Engineering) (SSC JE)

Total Questions: 50

1. Which of the following is NOT pure substance? [NHPC JE (ME) 06.04.2022 (Shift-II) ]

Correct Answer: (d) Air
Solution:

• A pure substance is always homogeneous and contains only one kind of atoms or molecules. A pure substance canot be separated into its constituents by physical methods.
• Air is not a pure substance
• Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapors and some other gases.

2. Per capita water demand is– [RRB JE 26.08.2015 (Shift-III) ]

Correct Answer: (c) annual average amount of daily water required by one person
Solution:

Per capita water demand is annual average amount of daily water required by one person.
• Per capita demand (q)

3. The continuous exposure of high concentration of carbon monoxide may cause? [RRB JE 26.08.2015 (Shift-III)]

Correct Answer: (d) coma followed by death
Solution:

High concentration of CO level are high enough, it may cause person in unconscious state or death.

Moderate concentration– Exposure to moderate and high level of CO over long periods of time has also been linked with incased risk of heart diseases.

Continuous exposure– People who survive serial CO poisoning may suffer long term heath problems.

4. The permissible desirable drinking water standard for total hardness is– [JSSC JE (GEN. ENGG.)- 31.10.2022 / RRB JE 26.08.2015 (Shift-III) ]

Correct Answer: (a) 200 mg/l
Solution:

5. In BOD₅ determination of sewage, the initial dissolved oxygen is measured to be 8.3 mg/l. However, after 5 day incubation at 20⁰C temperature, the dissolved oxygen is found to be 2.3 mg/l. If the dilution factor is 1:60, the BOD₅ of the sewage would be– [RRB JE 26.08.2015 (Shift-III) ]

Correct Answer: (c) cannot be determined
Solution:

6. The frequency range of audibility of a healthy person with perfect hearing is– [RRB JE 26.08.2015 (Shift-III) ]

Correct Answer: (c) 20 to 20,000 Hz
Solution:

The frequency range over which normal hearing occurs-approximately 20 Hz to 20,000 Hz. Above the range of 20,000 Hz, the term ultrasonic is used, below 20 Hz, the term subsonic is used.

• The normal audible range for loudness is from 0 to 180 dB, but anything over 85 dB can be damaging.

7. The green house gases as per their decreasing order of effectiveness are– [RRB JE 26.08.2015 (Shift-III) / RRB JE 29.08.2015 (Shift-I) ]

Correct Answer: (a) CO₂, CH₄, N₂O and CFC
Solution:

The major (GHGs) are listed–
(i) Carbon dioxide (CO₂) - 76%
(ii) Methane (CH₄) - 15%
(iii) Nitrous oxide (N₂O) - 6%
(iv) Chlorofluoro carbon (CFC) - 3%
• CO₂ > CH₄ > N₂O > CFC

8. The prescribed per capita water demand for small cities and town is– [RRB JE 26.08.2015 (Shift-I) / RRB JE 29.08.2015 (Shift-II) ]

Correct Answer: (a) 135 litres per capita per day
Solution:

As per IS : 1172-1993–The value of water supply given as 150 to 200 litres per head per day under normal conditions, may be reduced to 135 litres per head per day for house of lower income group and economically weaker section depending upon the prevailing conditions in small cities and towns.

9. The spacing between two bars in medium size screen ranges from– [RRB JE 26.08.2015 (Shift-I) ]

Correct Answer: (b) 20–40 mm
Solution:

Coarse screens– It is also known as racks and the spacing between the bar is about 50 mm or more. These screens do help in removing large floating materials.

Medium size screens– The spacing between the bar is about 6 to 40 mm, it is screenings usually contain same quantity of organic material, which may putrefy and becomes offensive and must, therefore, be disposal by incineration of burial (not by dumping).

Fine size screens– It have perforation of 1.5 mm to 3 mm in size. These screens, however, yet clogged very often, and need frequent cleaning. The fine screen is usually made of woven wire mesh with an opening not more than 6 mm² .

10. In small water supplies such as army troops, private plants and swimming pools, the most common disinfectants used are– [RRB JE 26.08.2015 (Shift-I) ]

Correct Answer: (d) Chlorine and bromine
Solution:

In small water supplies such as army troops, private plants and swimming pools, the most common disinfectants used are chlorine and bromine. Chlorine and bromine have the ability to neutralize most of the pathogenic microorganisms. If remains active when the pH level goes higher than 7.8.