The size of particles being studied in 'nano-technology' is about
- (a)1 Å – 10 nm
- (b)1 – 100 nm
- (c)1 – 50 μ
- (d)1 mm – 10 mm
Correct — B, 1 – 100 nm. The nanoscale is defined as the range of dimensions between about 1 and 100 nanometres, and nanotechnology is the understanding and control of matter at that scale. A nanometre is a thousand-millionth of a metre, so the window runs from a few atoms across up to a particle a thousand times smaller than the width of a human hair. The range is not an arbitrary bracket. Below it, matter is described as individual atoms and molecules; above it, a material behaves in bulk. Inside it, a substance can behave quite differently from the same substance in a lump — the melting point falls, the colour can change, the surface area per unit mass becomes enormous and quantum effects begin to show — and it is that difference that makes the field worth a name of its own.
- (a)1 Å – 10 nm — One angstrom is 0.1 nm, roughly the size of a single atom, so this range starts an order of magnitude below the nanoscale and stops a tenth of the way up it. It describes atomic dimensions rather than nanotechnology's working range.
- (c)1 – 50 μ — A micrometre is a thousand nanometres. This band covers dust, pollen grains and human cells — the domain of the ordinary optical microscope, not of the nanoscale.
- (d)1 mm – 10 mm — Millimetres are visible to the naked eye and stand a million times above the nanometre. Nothing about this range is nano.
Nanotechnology works with structures deliberately built or controlled at sizes of roughly one to a hundred nanometres. What makes it a distinct field is that properties change in this range: the proportion of atoms sitting at the surface becomes large, so reactivity and catalysis rise sharply, and quantum confinement can alter optical and electronic behaviour. Carbon nanotubes, graphene, quantum dots and nanoparticle drug carriers are the standard examples.
The four options are separated by whole powers of ten, so the item is really testing whether the prefixes are held securely — nano is 10⁻⁹, micro is 10⁻⁶, milli is 10⁻³, and an angstrom is 10⁻¹⁰ metres. Option (a) is the one that catches a candidate who recognises that both units are small; the check is that an angstrom is atomic and so lies below the nanoscale rather than at its start. Anchoring to the exam year and beyond: in 2021 India's programme in this area ran through the Nano Mission of the Department of Science and Technology, set up in 2007, and nanoscale materials had already reached everyday use in sunscreens, coatings and electronics. That direction of travel has continued rather than reversed, with nanoparticle carriers now familiar from vaccine delivery.
- Nanotechnology is the understanding and control of matter at dimensions between roughly 1 and 100 nanometres.
- One nanometre is 10⁻⁹ metre; one angstrom is 0.1 nanometre and one micrometre is 1000 nanometres.
- At the nanoscale a material can show optical, chemical and mechanical properties unlike those of the same substance in bulk.
- The very large surface area per unit mass of nanoparticles is what makes them useful as catalysts and carriers.
- Carbon nanotubes, graphene and quantum dots are the standard nanoscale materials of the syllabus.
- Reading angstrom as a nanoscale unit; it is ten times smaller and describes atomic dimensions.
- Mixing up the micro and nano prefixes, which differ by a factor of a thousand.
- Assuming a nanoparticle behaves like a small lump of the same material — the point of the field is that it does not.
As a size-range item, as a statement set on applications in medicine and materials, or through a named nanomaterial such as graphene.
With reference to the use of nanotechnology in health sector, which of the following statements is/are correct? 1. Targeted drug delivery is made possible by nanotechnology. 2. Nanotechnology can largely contribute to gene therapy.
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(c) Both 1 and 2
The same field asked for what it can do rather than how small it is. Both of its statements are accepted — nanocarriers make targeted drug delivery possible and nano-vectors are being developed for gene therapy — and both applications depend on working inside the size band this question defines.
- practice — not a real PYQ
One nanometre is equal to
- (a)10⁻⁶ metre
- (b)10⁻⁹ metre
- (c)10⁻¹² metre
- (d)10⁻³ metre
Answer(b) 10⁻⁹ metre — a thousand-millionth of a metre; 10⁻⁶ is a micrometre and 10⁻³ a millimetre.
- practice — not a real PYQ
Which one of the following is a nanomaterial made of carbon?
- (a)Graphene
- (b)Bakelite
- (c)Nichrome
- (d)Vulcanised rubber
Answer(a) Graphene — a single layer of carbon atoms one atom thick, and one of the standard nanoscale materials alongside carbon nanotubes and fullerenes.