Is a chocolate milk shake a solution?
No chocolate milk is an emulsion or suspension. The globules of fat are not dissolved but in suspension as an emulsion.
It is a solution. For chocolate syrup and milk to be a mixture you would have to be able to mix it together and then separate them, making chocolate syrup and milk again. You can't do this. When you mix them together it makes a completely new substance that cannot be changed back to the things that you orignally had. Therefore it is not a mixture.