There is some concern regarding the nanoparticles of some chemical elements that are used by the industry in the manufacture of various products. Why? 1. They can accumulate in the environment, and contaminate water and soil. 2. They can enter the food chains. 3. They can trigger the production of free radicals. Select the correct answer using the code given below.

States that industries dispose wastes (including poisonous elements and heavy metals) into rivers, lakes and soil, causing these elements to reach and affect water bodies.

A student could extend this by noting that if bulk elemental wastes reach water/soil, then engineered nanoparticles of those elements released similarly could also be transported and accumulate in the same environmental compartments.

Lists specific elemental pollutants in industrial waste (mercury, lead, copper, zinc, cadmium, etc.), showing industry uses and emits metal elements.

Knowing industries emit elemental metals, one can reasonably suspect industry might also release those elements in nanoparticulate form which could follow analogous accumulation pathways.

Describes inorganic pollutants from chemical plants (chlorides, sulphates, nitrates of metals, suspended particles) and notes landfill/solid wastes pollute surface and groundwater.

Since suspended particles and metal salts enter water/groundwater, a student could infer that particulate forms including nanoparticles may likewise persist and accumulate in sediments and aquifers.

Explains chemical fertilizers and synthetic organic compounds flow into water bodies and can accumulate (e.g., nitrates causing eutrophication), illustrating environmental accumulation of applied chemicals.

By analogy, this pattern of chemical runoff and accumulation supports the possibility that nanoparticulate chemical forms released to land or water might also concentrate and impact ecosystems.

Notes certain industrial by-products (perfluorocarbons, sulfur hexafluoride) have long atmospheric lifetimes and are associated with manufacturing processes.

This provides an example of industrial chemicals that persist and travel in the environment, suggesting nanoparticles produced or emitted by similar industries could likewise be persistent and transportable before eventual accumulation.

Describes how particles (sulphuric acid particles) can liberate reactive atoms (free chlorine) that then participate in further chemical reactions.

A student could generalize that small particles or aerosols can release reactive species and ask whether metal or element nanoparticles similarly release atoms or reactive fragments that form free radicals.

Explains that different metals have differing reactivities with oxygen and that metal surfaces form oxide layers, implying surface chemistry and reactivity vary with element and form.

A student could infer that nanoscale forms (much higher surface area) might alter oxidation behavior and thus influence radical-generating reactions with oxygen.

Notes industries release chemical residuals and heavy metals into the environment, providing context that industrially used elements and their residues are present where radical-generating processes could occur.

Combine this with knowledge of nanoparticle release to consider environmental exposure pathways where nanoparticles could undergo reactions producing radicals.

Lists industrially produced compounds and by-products from manufacturing and semiconductor processes, indicating many reactive chemical species are associated with industry.

Use this to identify specific industrial elements/compounds that, when present as nanoparticles, could participate in surface or redox chemistry leading to radical formation.

Shows examples of redox reactions involving metal oxides and metals (ZnO reduced to Zn), illustrating that metal compounds can undergo reactions that change oxidation states.

A student could extend this to ask whether nanoscale metal oxides more readily undergo redox steps that can produce radical species (e.g., via Fenton-like chemistry).