Step-by-step explanation:
this is a very easy question, you just need to know the formula of density, the mass and volume.
you're given the mass of the iron which is 28.5g and when it is submerged into a cylinder containing 45.50 ml, it rises to 49.10 ml. the volume of water displaced gives you the volume of the iron. thus,
V² - V¹ = 49.10 ml - 45.50 ml
V of iron = 3.6 ml
now that you know both the mass and volume, you can work out the question.
density (ρ) = mass / volume
ρ = m/v
ρ = 28.5 g / 3.6 ml
ρ = 7.916666...
ρ = 7.92 g/ml (3 sf)
hope this helps you!
- s.