What percent of strontium 87 remains after 4 half lives

Why do german shepherds shed so much

What are the most explosive events that occur on the sun? umbras solar flares solar winds prominences

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind