The ion with the smallest diameter is . The ion with the smallest diameter is . Be2 Sr2 Ca2 Ba2 Mg2

Be2^+

Explanation:

Ionic diameter increases down the group. This implies that Be2^+ will have the smallest diameter.

This extremely small diameter makes Be2^+ to differ considerably from other ions of group 2 elements.

For instance, the compounds of beryllium are mostly covalent in nature.

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