What's the density of a substance if the mass is 3.1g and it occupies 4.1 ml?

The density of a substance is given by the formula ρ = m/v, where m is the mass of the substance, and v is the volume.

ρ = m/v
ρ = 3.1 g / 4.1 mL
ρ = 31/41 g/mL = 0.756 g/mL = 0.756 g/cm^3

Mgo2 is the oxidation state of manganese oxide

Elias is almost correct. he just got it backwards.the correct answer is that it demonstrates elastic potential energy transforming into kinetic energy.