Yes a solution does have to involve liquid. For example. when when dissolving a solid you must have liquid to do so. And it also must contain liquid for another liquid. The Fact f one substance dissolving into another substance will require liquid.
No, not always. There is always going to be solutions of gases in the air. And, there may be a solution of metals in alloys.
Basically, a solution is just any of the same mixture, which is solid-solid, liquid-liquid, and gas-gas.
A solution can exist not only in liquid form but also as solids and gases. Liquid solutions, solid solutions (like alloys), and gaseous solutions (like air) are all examples. Understanding the concept of solutions in different states broadens their application in various fields.
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