Pure water may be identified by its density: it will have the lowwest density of the three solutions, given that the solutes (salt and sugar) increase the density (this is the easiests and quickest way).
You can also measure the freezing points or boling points to identify the pure water because the solutes depress the freezing points and increase the boling points.
To differentiate sugar water and salt water, you can probe which one conducts electricity, because salt water is a conductor (given that it ionizes into Na+ and Cl-) but sugar water is not a conductor.
Answer:
0.56L
Explanation:
This question requires the Ideal Gas Law: 
where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the Ideal Gas constant, and T is the Temperature of the gas.
Since all of the answer choices are given in units of Liters, it will be convenient to use a value for R that contains "Liters" in its units:
Since the conditions are stated to be STP, we must remember that STP is Standard Temperature Pressure, which means 
and 
Lastly, we must calculate the number of moles of 
there are. Given 0.80g of , we will need to convert with the molar mass of . Noting that there are 2 oxygen atoms, we find the atomic mass of O from the periodic table (16g/mol) and multiply by 2: 
Thus, 
Isolating V in the Ideal Gas Law:
...substituting the known values, and simplifying...
So, 0.80g of would occupy 0.56L at STP.
A. Covalent bonds is the answer
The correct answer would have to be true
