Nokea
What is meant by the term TTHM, and why is it relevant to water quality?
- A. Trihalomethanes formed during chlorination; potential carcinogens.
- B. Toxic trace heavy metals; cause immediate poisoning.
- C. Total thermal heat management; regulates temperature.
- D. Temporary total hardness measure; affects taste.
Correct Answer: A
Rationale: TTHMs are disinfection byproducts linked to cancer risks, making them critical for water quality monitoring.
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Vibrio cholera are destroyed by all except
- A. boiling
- B. drying
- C. bleaching powder(1 mg/lit.)
- D. cresol
Correct Answer: D
Rationale: Cresol is not effective against Vibrio cholerae, while boiling, drying, and bleaching powder are effective methods for destroying the bacteria.
The interquartile range covers what proportion of a distribution?
- A. 25%
- B. 50%
- C. 75%
- D. 100%
Correct Answer: B
Rationale: The IQR spans the middle 50% of the data.
Define the following terms: latency
- A. The time between exposure to a hazard and the onset of symptoms.
- B. The strength of a chemical bond.
- C. The period during which a disease is contagious.
- D. The duration of a clinical trial.
Correct Answer: A
Rationale: Latency refers to the delay between exposure to a harmful agent and the manifestation of health effects.
Define in your own words the term 'risk factor'.
- A. A characteristic or exposure that increases the likelihood of developing a disease.
- B. A factor that decreases disease risk.
- C. A protective measure against illness.
- D. A statistical anomaly in health data.
Correct Answer: A
Rationale: A risk factor is any attribute, characteristic, or exposure that increases the probability of an individual developing a disease or health condition.
Randomization is done in experimental study:
- A. to eliminate selection bias.
- B. to select control
- C. to eliminate confounding bias
- D. all of above
Correct Answer: D
Rationale: Randomization helps to eliminate selection and confounding biases while selecting controls.