The main difference between compounds and mixtures is......?

e

I agree, this is poorly worded for a conclusive answer, all of these could be true or false depending on the situation and how you choose to react it or make a mixture.

I would say e only because in a mixture, there is not necessarily a chemical bond between the solvent and solute in solution. However, intermolecular forces which can be considered somewhat of a chemical bond are present, especially in soothing like putting salt in water.

Compounds are chemically bonded, while a mixture does not necessarily react or chemically bond in the same way. But, there are cases in mixtures where chemical bonds do form in reactions, so e is also false. But, who knows what they were going for.

This is one of "THOSE" science questions that is so poorly conceived as to have more than one answer and no correct answers. So... getting a "correct" answer is not really a demonstration of any understanding of fundamental scientific concepts.

Sorry to dump on you as the student. But, you might ask your teacher about some of the point below.

So... let's consider the potential answers...

a) whoever wrote this must believe that the cost is somehow related to the chemical characteristics of matter. Very interesting theory, sort of along the lines of: this thing is yellow so it must taste like a banana.

b) so students who are being tested on whether they understand

the difference between a compound and a mixture are supposed to understand exactly what "heavy metals" are?

c) Since I assume the author does NOT think this is a correct answer, does the author believe that it is impossible to have a mixture of two or more elements added in specific proportions? I could add a given mass of pure iron to a vessel containing a given mass of helium gas and be very specific about the proportions based on moles, mass or volume. Does that make this a compound rather than a mixture? Or, if a compound can be formed with varying proportions of elements then it is mixture? Say, say different specific proportions such as NaCl with a 100 ppm of K vs NaCl with a 100 ppm of Li?

d) So, does the author believe that chemical reactivity depends on whether the matter is a compound or a mixture, and this is, therefore, a defining characteristic? A compound such as Al2O3 is about as unreactive as compounds get but a compound such a tri-nitro-tolulene (TNT) is towards the other end of the reactivity spectrum.

e) so the author believes that chemical bonding is impossible in mixtures? Therefore, a piece of gold and a peanut can be a compound if they are chemically bonded together with, for example, epoxy.

I am, perhaps, being overly critical. Chances are that the teacher of this class had no voice in the selection of textbook nor test questions.

A chemical reactions yields compounds. While a mixture is just mixing different components physically.

The proportions of elements in a compound are fixed while the components can be in any proportion in a mixture.

Separation of a mixture is easily done by some physical processes while separating components in a compound is not that easy.

Also the cost of a compound depends on the elements of the compound and the processing done to yield the compound. The cost of mixture is merely the sum of the cost of its individual components.