Help. I think I understand but want a better description than just my textbook

What is the formula that this ionic compounds could form sr2+p3-o2-

There are 6.022, 104 atoms of hg in 1 mole of hg the number of atoms in 45 moles of hg can be found by multiplying 4.5 by 6.022, 102 which is the number of atoms in 4.5 moles of hg, correctly written in scientific notation with the correct number of significant figures? 0 21,109 0 21,100 271, 1024 27.099, 100 mark this and retum save and exit submit

Draw the skeletal structures of two different molecules that are each made of 5 carbon atoms and 12 hydrogen atoms.