Why would an atom with high electronegativity be a great match for an atom with low ionization energy?

Because the easier a metal donates an electron (Low Ionization Energy), the more readily a non-metal with high electromagnetically will accept it.  

Thus they match well, - one readily donates, the other readily accepts. This is how ionic bonding occurs.  

Hope this helps.

where are the choice options?

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3