(P1)(V1)=(P2)(V2)
(2.52 atm)(125 L)=(1.50 atm)(x L)
(315)/(1.50)=(V2)
V2=210 L
Sorry this isnt an answer but this is a lot of work, if you really need it answered make it worth more points :)
A because you can prove that with the graph you are given in the wuestion
The Lewis dot structure of Mg²⁺ is shown in the picture attached.
In Mg atom, the outermost orbit has 2 electrons.
The atom has the ability to lose its 2 electrons to become Mg²⁺
The Mg²⁺ ion have completed its vacancy in the second orbit having 8 electrons.
Therefore, the valency of Mg becomes 2+ as it loses its electron.