Lanthanoid, what is another common name for this group of elements?

What is the polyatamic ion of borate

May someone me with these science questions

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.