Difficulty: Easy
Correct Answer: 0.001 mg/l
Explanation:
Introduction:
Mercury is a toxic heavy metal with severe neurological and developmental impacts, especially in methylmercury form. Strict limits in potable water reduce chronic exposure. Water standards specify low microgram-per-liter levels to protect public health and to guide treatment plant monitoring and corrective actions.
Given Data / Assumptions:
Concept / Approach:
The standard limit for mercury in drinking water is set at the microgram-per-liter scale. A widely recognized compliance value is 0.001 mg/L (which equals 1 μg/L). This threshold reflects achievable analytical detection, treatment capability, and health-based risk assessments.
Step-by-Step Solution:
Interpret units: 0.001 mg/L = 1 μg/L.Compare listed options to typical regulatory limits in potable water.Select 0.001 mg/L as the maximum allowable/desirable concentration.
Verification / Alternative check:
Public health guidance documents and water-quality manuals consistently specify mercury limits at or below 1 μg/L for treated drinking water, aligning with this numeric selection.
Why Other Options Are Wrong:
Common Pitfalls:
Misreading mg/L versus μg/L; always convert correctly to interpret toxicity thresholds.
Final Answer:
0.001 mg/l
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