How many atoms are there in 5.7 mol of hafnium?

Arollercoaster car at the top of a hill has potential energy kinetic energy chemical energy light energy

In the following table, all the columns for the element calcium are filled out correctly. element electron structure of atom electron structure of ion net ionic charge calcium 1s22s22p63s23p64s2 1s32s22p63s23p64s1 +1 true false

Water is a highly important natural resource. which of these would be the best method to conserve water? a) drinking bottled water b) monitoring the ph of rivers c) treating and re-using wastewater d) testing nitrate levels in groundwater