Density of a substance is defined as the mass of the substance divided by the volume.
Density of the substance= 0.242 g cm⁻³
volume of the substance= 2.50 in³
As, 1 in³= 16.39 cm³
So, 2.50 in³= 16.39× 2.50 cm³=40.97 cm³
As ,
Mass=volume ×Density
Mass=40.97 × 0.242
Mass=9.916 g.