What is necessary in order to build an ionic compound?

Can someone me with 3 and 4 plz. this is for masteries test.

What is the compound name for the formula [ru(en)2cl2]2+ and [co(en)cl2br]-

Which statement best summarizes the importance of ernest rutherford’s gold foil experiment? it proved that all of john dalton’s postulates were true. it verified j. j. thomson’s work on the atomic structure. it showed that an electron circles a nucleus in a fixed-energy orbit. it showed that a nucleus occupies a small part of the whole atom.