Question

The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be $1000 \,ppb$, $40\, ppb$, $100\, ppm$ and $0.2\, ppm$, respectively. This water is unsuitable for drinking due to high concentration of :

• A. Fluoride
• B. Lead
• C. Nitrate
• D. Iron

Answer 1

The Correct Option is C

To determine why the water sample from the underground lake is unsuitable for drinking, we need to evaluate the concentrations of each contaminant against the acceptable limits set by guidelines such as those from the World Health Organization (WHO) and other regulatory bodies.

1. Concentration Details:
   • Fluoride: 1000 \, \text{ppb} or 1 \, \text{ppm}
   • Lead: 40 \, \text{ppb}
   • Nitrate: 100 \, \text{ppm}
   • Iron: 0.2 \, \text{ppm}
2. Acceptable Limits:
   • Fluoride: According to WHO guidelines, the acceptable limit is 1.5 ppm. Thus, 1 ppm is within the safe range.
   • Lead: The WHO sets the limit at 10 ppb. Hence, 40 ppb is above the safe level, indicating toxic levels of lead.
   • Nitrate: The guideline for nitrate is typically around 10 ppm. At 100 ppm, nitrate is well above the safe drinking limit.
   • Iron: Iron is generally acceptable up to 0.3 ppm for drinking water. Thus, 0.2 ppm is within the allowable limits.
3. Determination:

   The nitrate concentration is 100 \, \text{ppm}, which is significantly higher than the recommended limit of approximately 10 \, \text{ppm}. This high level of nitrate makes the water unsuitable for drinking.

4. Conclusion:

   Therefore, the correct answer is that the water is unsuitable for drinking due to the high concentration of Nitrate.