Boron (b) has two naturally occurring isotopes: boron-10 (abundance = 19.8%,

mass = 10.013 amu) and boron-11 (abundance = 80.2%, mass = 11.009 amu).

calculate the atomic mass of boron.

What is the relation between concentration of reactants and the rate of chemical reaction?

6. using 3 – 4 sentences explain (in your own words) why water expands when it freezes? 7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation.

How many moles of bromine are needed to produce 3.23 moles of potassium bromide