Types of Mix tures
In a homogeneous mixture the components are uniformly mixed and it will have single phase.
In heterogeneous mixture are not mixed thoroughly or uniformly, and it will have more than single phase.
Mix some Iron filings and common salt in a glass plate. Observe.
We can see that in the case of sugar we get a clear solution and the particles never settle down. In the case of oil and water we first get a cloudy mixture which separates into layers after a while. In the case of flour mixed with water we get a very turbid mixture and fine particles slowly settle down at the bottom after some time. We can call the first mixture as homogeneous mixture and a true solution. The second one was apparently homogeneous for a while but separated into layers, leaving behind some cloudiness. This is called a colloidal solution. The third one is heterogeneous and is called a suspension in which the particles settle down at the bottom.
Try this on your own
The longest wavelength of red light (almost infrared) that most people can see is 7.5 × 10-7 meters. What is this in nanometres?
Length in nm = (length in m) × (109 nm/m)