Do solutions have a definite composition?

Answer 1

Definite proportions, not indefinite proportions. What it says is that the composition of a compound is the same regardless of its state. For instance: Water is 11.1% hydrogen and 88.9% oxygen by mass. If I were to freeze water into ice, its composition would be 11.1% hydrogen and 88.9% oxygen by mass. If I were to vaporize the water into steam, its composition would be 11.1% hydrogen and 88.9% oxygen by mass. If I were to take ice, melt it, use an electrical current to electrolyze it into hydrogen gas and oxygen gas, burn them together to form water, flash freeze the resulting water to a temperature of -200 oC, it would still have a composition that is 11.1% hydrogen and 88.9% oxygen by mass. That is what the law of definite proportions tells you.

Answer 2

The law of constant composition applies to compounds.

Answer 3

If you think to the "law of definite proportions" this is now considered as not universally valid. An example are the non-stoichiometric compounds.

Answer 4

yes