What is a ca+ in chemistry? is it a positive ion?

Theoretically, which metal should be the most reactive? hydrogen lithium francium fluorine

After cloud droplets form, what must happen to them for precipitation to occur?

Between 2014 and 2016, more than 25,000 children in flint, michigan, drank water that was contaminated with lead from lead pipes. during this time, the city claimed the water was safe to drink. which of these actions could the city have taken to ensure that the drinking water was free from lead?