After 30 days, 5.0 grams of a radioactive isotope remains from an original 40.-gram sample. what is the half-life of this element?

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.

What volume of a 0.0606 m solution of strontium bromide is needed to obtain 0.340 mol of the compound? question 42 options: a)5.61 l b) 3.4 l c) 600 ml d) 1 l e) 178 ml

Under which circumstances are kp and kc equal for the reaction aa(g)+bb(g)⇌cc(g)+dd(g)?