The correct options are
A [Al3+]=[Na+]
C [SO2−4]=[Na+]+[Al3+]
ppm = number of milligrams present in 1 litre of the solution
Given
Mass of Al2(SO4)3=3.42 mg
Mass of Na2SO4=1.42 mg
[Al2(SO4)3]=3.42×10−3342=0.01×10−3 M
[SO2−4]=0.03×10−3 M
[Al3+]=0.02×10−3 M
[Na2SO4]=1.42×10−3142=0.01×10−3 M=[SO2−4]
[Na+]=0.02×10−3 M
total concentration of [SO2−4] =0.04×10−3 M
Hence in solution
[Na+]=0.02×10−3 M
[SO2−4] =0.04×10−3 M
[Al3+]=0.02×10−3 M
So,
[Al3+]=[Na+] and [SO2−4]=[Na+]+[Al3+]