Consider an element Z that has two naturally occurring isotopes with the following percent abundances: the isotope with a mass number of 17 is 45% abundant; the isotope with a mass number of 20 is 55 % abundant. What is the average atomic mass for element Z?​

Answer explain why it is not possible to deduce a complete order of reactivity.

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 !

3.09 lab: reaction of metals 1 which combinations of substances resulted in a chemical change? for each metal that participated in a chemical change, write the type of metal it is, based on your examination of the periodic table. were there any metallic compounds that did not react with either the acid or the base? write the type of metal, based on your examination of the periodic table. make a general statement about the reactivity of the metals in this experiment.