A radioactive material initially has an activity of 800 counts per second. Eight hours later it has an activity of 200 counts per second. Find the materials half life

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.