Fluorine-21 has a half life of approximately 5 seconds. What mass of 3.0 mg 1 point will remain after 25 seconds.

How many moles of oxygen gas are produced from the decomposition of six moles of potassium

Which rate indicates the number of children that would be born per woman if she were to live to the end of her child bearing years

Need what is special about water as a compound? how does water regulate climate? what drives water evaporation?   why is the water vapor fresh water when it rises from the ocean? why might freshwater in the form of snow take longer to enter the water cycle again than liquid precipitation?   what is an aquifer? what role do people play in the water cycle? plz just answer as many as you can ! thx if you !