I think the answer is true.
D. A mixture
If the water is evaporating while the salt remains, it means the two are not chemically bonded and therefore are not a compound.
They discovered that *elements* show increase in atomic numbers across the period.
Answer:
16,,24Mg 17,,a24.1 18a mass number of the most abundant isotope
Explanation:
atomic number of Mg is 12 ,therefore its mass number should be the value that is very close to 24.
24.1 is the value of thee most abundant isotope.