Which of the following statements about heavy metals is true?

• A. All heavy metals are essential nutrients for humans.
• B. Heavy metals cannot form compounds with nonmetals.
• C. Heavy metals are always highly reactive with water.
• D. Heavy metals are generally defined by having a high atomic mass and can be toxic to living organisms.

Answer: (D)

Verified step by step guidance

1. Understand the definition of heavy metals: They are typically elements with high atomic masses and densities, often found in the d-block or f-block of the periodic table.
2. Evaluate the statement 'All heavy metals are essential nutrients for humans.' Consider that while some heavy metals like iron and zinc are essential, many others are toxic and not required by the body.
3. Analyze the claim 'Heavy metals cannot form compounds with nonmetals.' Recall that heavy metals often form compounds such as oxides, sulfides, and halides, which involve bonding with nonmetals.
4. Consider the statement 'Heavy metals are always highly reactive with water.' Reflect on the fact that reactivity with water varies among heavy metals; some react slowly or not at all under normal conditions.
5. Conclude that the true statement is that heavy metals are generally defined by their high atomic mass and potential toxicity to living organisms, which aligns with their chemical and biological behavior.