Environmental health: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Environmental health

Sample item

What does residual chlorine in treated drinking water primarily indicate?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Ongoing disinfecting capacity after initial treatment

A measurable residual chlorine level indicates that some disinfectant remains after initial demand has been met, helping protect water against microbial recontamination during storage and distribution when managed safely.

Option by option

  • A. Amount of dissolved oxygen only

    Dissolved oxygen is a separate water-quality parameter.

  • B. Ongoing disinfecting capacity after initial treatment (correct)

    Correct: residual chlorine indicates continuing disinfectant protection.

  • C. Presence of fluoride only

    Fluoride content is measured independently of chlorine residual.

  • D. Total hardness of water

    Hardness reflects calcium and magnesium salts.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More PSM questions

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, Ongoing disinfecting capacity after initial treatment. A measurable residual chlorine level indicates that some disinfectant remains after initial demand has been met, helping protect water against microbial recontamination during storage and distribution when managed safely.

Why is "Amount of dissolved oxygen only" not the answer?

Dissolved oxygen is a separate water-quality parameter.

Why is "Presence of fluoride only" not the answer?

Fluoride content is measured independently of chlorine residual.

Why is "Total hardness of water" not the answer?

Hardness reflects calcium and magnesium salts.

What concept does this question test?

It tests Environmental health in PSM. The correct option holds because: Correct: residual chlorine indicates continuing disinfectant protection.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Environmental health?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.