Answer is: volume will be 6,7 L.
Boyle's Law: the pressure volume law - <span> volume of a given amount of gas held varies inversely with the applied pressure when the temperature and mass are constant.
p</span>₁V₁ = p₂V₂.
90 kPa · 5 L = 67 kPa · V₂.
V₂ = 90 kPa · 5 L / 67 kPa.
V₂ = 6,7 L, but same amount of oxygen.
Copper (I) oxidation state is 1 Cu2So4
copper (II) oxidation state is +2 CuSo4
copper (i) also give up one electron so you need two of them to react with the sulfate ion (which has charge of -2)
and also all metallic ions have an multiple oxidation levels corresponding to the number of electrons they can exchange or loose
Hope this helps
