Q.The particle size of ZnO material is 30 nm. Based on the dimension it is classified as

The peacock feather's iridescent colour comes from a natural photonic nanostructure (periodic nanoscale layers), making it a genuine natural nanomaterial — unlike a grain of sand, whale skin, or a peacock's beak.

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Nanomaterials are materials with structural features at the nanometre scale (1-100 nm) that give rise to distinctive, size-dependent properties. Nanomaterials occur both naturally and can be engineered.

• Peacock feather: its brilliant, shifting (iridescent) blue-green colours are not due to pigment but to periodic, nanoscale photonic crystal-like structures within the barbules of the feather that interfere with light of specific wavelengths — a classic textbook example of a natural nanomaterial (structural colour).
• Grain of sand, whale skin, and peacock beak are ordinary macroscopic biological/mineral materials without such a defining nanoscale structural feature.

Nanotechnology is the science of engineering matter at the nanometre scale, where materials can behave very differently from their bulk form.

Nanotechnology refers to the science, engineering, and application of materials and devices whose structures are controlled and built at the nanoscale — typically with at least one dimension between about 1 and 100 nanometres ($1\,\text{nm}=10^{-9}\,\text{m}$).

At this scale, materials frequently exhibit properties (electrical, optical, mechanical, chemical) that are markedly different from the same material in bulk form, because quantum mechanical effects and a very high surface-area-to-volume ratio become significant.

Applications relevant to physics/electronics include the fabrication of nanoscale semiconductor devices (enabling ever-smaller, faster, and more efficient transistors and integrated circuits), nano-sensors, and novel materials such as carbon nanotubes and quantum dots used in advanced electronic and optical devices.