Which of the following is an example of a chemical contaminant?

• A. Sand particles in a river
• B. Plastic debris floating in the ocean
• C. Lead ions (Pb^{2+}) in drinking water
• D. Microorganisms in untreated water

Answer: (C)

Verified step by step guidance

1. Understand the definition of a chemical contaminant: it is a substance that is a chemical in nature and is present in an environment where it can cause harm or unwanted effects.
2. Analyze each option to determine if it is chemical or non-chemical: sand particles and plastic debris are physical contaminants (solid particles), and microorganisms are biological contaminants (living organisms).
3. Identify that lead ions (Pb^{2+}) are chemical species dissolved in water, making them chemical contaminants.
4. Recognize that chemical contaminants typically involve dissolved ions or molecules that can affect water quality and health.
5. Conclude that among the options, lead ions (Pb^{2+}) in drinking water are the example of a chemical contaminant.