2. Sample Papers
  3. Railways
  4. General Science & Technology
  5. Pollution of Air and Water

Railways General Science & Technology Pollution of Air and Water Sample Paper Water Pollution Sample Test Paper-21

  • question_answer
    ______ is the first step of sewage treatment.

    A)  Precipitation     

    B)  Chlorination

    C)  Sedimentation

    D)         Aeration

    Correct Answer: C

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