'I shall now make some sugar vanish by putting it into a beaker of water!!'
Cool magic trick! But what has actually happened to that vanishing sugar?
It has dissolved. Dissolving a solid into a liquid is a common way that mixtures are made.
Dissolving will only happen if the solid is soluble - that means it will break up into such small pieces that they completely spread out in the liquid and form a transparent solution, which is one that you can see through - the solid is not visible.
In a solution, when a solid dissolves in a liquid, the solid particles which were held tightly together in a fixed arrangement are broken up by the liquid particles as it dissolves.
The solid substances that dissolve are called solutes and the liquids they are dissolved in are called solvents. A solute dissolved in a liquid makes a solution. In a sugar solution, sugar is the solute and water is the solvent. The particles of solute and solvent are completely mixed together - they are now a mixture.
So we know that substances that dissolve are said to be soluble, but how about those that don't? Well, solids that do not dissolve are said to be insoluble.
Solids that are insoluble can still form mixtures with liquids. When an insoluble substance is mixed with a liquid it can either form an opaque mixture or a suspension.
In an opaque mixture, the solid has been broken up slightly when it was mixed with the liquid but not into small enough pieces to dissolve. Instead, the small pieces are suspended in the liquid and spread out making the mixture look cloudy or opaque. Milk is an example of an opaque mixture.
Suspensions are a mixture where large, insoluble particles of a solid start off suspended in a liquid, but will eventually settle to the bottom and you will see two layers - the solid at the bottom with the liquid on top, quite separate from each other.
An example of a suspension is sand in water. When it is initially stirred, the sand particles are suspended in the water. However, after some time passes, the sand will sink to the bottom.
Let's look at some examples of different mixtures in the questions now.