To find the density of gallium, we can use the concept of weighted average density. Since gallium is located between aluminium and boron in the periodic table, we can assume that its density is also between these two values:

Density of gallium = (Density of aluminium + Density of boron) / 2

Density of gallium = (2.70 g/cm³ + 2.08 g/cm³) / 2

= 4.78 g/cm³ / 2

= 2.39 g/cm³

Therefore, the density of gallium is approximately 2.39 g/cm³.