Is Air a Heterogeneous Mixture or a Solution?

[temaire]

Homework Statement

Air is a mixture of 78% nitrogen, 21% oxygen, 0.09% of argon, and 0.03% of carbon dioxide. What can be said about air?

a) Air is a heterogenous mixture
b) Air is a pure substance, and is made up of N, O, Ar, and C
c) Air is a solution, in which nitrogen is the solvent
d) Air is a solution, in which nitrogen is the solute

Homework Equations

None

The Attempt at a Solution

I put c). Am I right?

 

[Gokul43201]

Yes. Do you understand why this is correct?

 

[temaire]

I got the answer mostly because I thought that the other choices were not correct answers. Also, since nitrogen makes up most of our air, I thought that it would be the solvent. If my reasoning is not going in the right direction, could you help me please?

 

[Gokul43201]

That's essentially correct.

A heterogeneous mixture must have more than one phase - not the case with air as described in the question (though real air is filled with all manner of solid particulates). Air is not a compound - it can be separated into its constituent gases by "physical" means, and its composition is definitely not fixed.