Answer:
coral bleaching is when the temperature of the water changes (even slight changes in temperature effect coral) and the coral reacts negatively to it causing it to die. unfortunately corals cannot recover once they have been bleached.
It is two or more objects and different things that can be removed from each other.
Answer:
B. control rods and moderators
The reactivity of metals increases as you move left in a period and as you move down in a group, so Marie needs to know the period and group of the element inside each box. Boxes that show locations in groups 1 or 2 or in period 8 contain the most reactive elements.