OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What distinguishes nano-silver particles from regular silver powder?

1. Nano-silver particles have a smaller volume

2. Nano-silver particles have a larger exposed surface area

3. Nano-silver particles are toxic

4. Nano-silver particles are less stable

The correct answer is: Nano-silver particles have a larger exposed surface area

Nano-silver particles are indeed distinguished from regular silver powder primarily by their larger exposed surface area. This characteristic leads to several important implications in various applications, particularly in medicine and technology. Due to their small size, nano-silver particles possess a significantly greater surface area relative to their volume compared to larger silver particles. This increased surface area enhances their reactivity, allowing for more effective interactions with biological systems, such as bacteria or viruses, which is why they are often employed for their antimicrobial properties. The larger surface area therefore contributes to their effectiveness in various applications, including coatings, textiles, and wound dressings, where the goal is to inhibit microbial growth. While the other options may contain elements of truth, they do not accurately capture the key distinction that defines nano-silver and contributes to its unique properties and applications. This understanding of surface area and its impact on reactivity and effectiveness is crucial for grasping the significance of nano-silver in scientific and industrial contexts.