What is the approximate size of a typical nanoparticle?
50 mm
50 µm
50 nm
Which statement about nanoparticulate substances is correct?
Their properties are usually the same as the substance in bulk
Their properties are usually different from the substance in bulk
Their nanoparticles can be seen with a light microscope
Why are zinc oxide nanoparticles used in sunblock creams?
They give you white streaks on your skin that look really cool
They block harmful visible light but let ultraviolet light through
They block ultraviolet light but do not reflect visible light
Which statement about nanoparticles is correct?
They have large surface areas compared to their volumes
They cannot be used as catalyst
They are always compounds such as zinc oxide
Which of these is a possible risk of nanoparticles?
They may be too small to see with the naked eye
They may be too small to be useful
They may be toxic
Which of these objects is the smallest?
Silver atom
Silver nanoparticle
Silver bar
About how many atoms do nanoparticles usually contain?
One
Hundreds
Tens of thousands
What happens to the surface area to volume ratio as the particle size decreases?
It decreases
It stays the same
It increases
A cube-shaped nanoparticle has sides 100 nm across. What is its surface area to volume ratio?
0.06
0.6
6
How many nanometres are there in a metre?
One thousand
One million
One billion