A student precipitates her ions out of solution, then places it in a hot water bath. After removing it from the water bath, the white precipitate disappeared. At this point, what can you conclude about the ions in her unknown?

more info ? ? i don't understand what the question is

explanation:

first one is the correct answer

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

i believe the answer is a.