So basically, the change in color effects the amount of cations in the solution making it a physical change rather than a chemical one, defying the law of conservation of mass! I hope this helped! (The only time the change in color affects the amount of cations is in the Alkaline Earth Metals)
source: college science teacher
Answer is: volume of methane is 78.4 mL.
n(CH₄) = 0.0035 mol.
At standard pressure and temperature:
V(CH₄) = n(CH₄) · Vm
V(CH₄) = 0.0035 mol · 22.4 L/mol.
V(CH₄) = 0.0784 L · 1000 mL/L = 78.4 mL.
Vm - molar volume.
Answer:
It is a pure substance. Magnesium is an element.
Reacting with metals is not a common property of bases. Bases do however react with acids.