Which of the following salts has the greatest molar solubility in pure water?

detailed solution

Correct option is C

For CaCO3, solubiliry can be calculated asCaCO3⇌CaS2++CO32S Ksp=S⋅S=S2⇒S=Ksp =8.7×10−9=0.0051=9.3×10−5For CuS, solubility can be calculated asCuS⇌Cu2++SS2− Ksp=S⋅S=S2 S=Ksp=8.5×10−45=85×10−46 =85×10−23=9.21×10−23  For Ag2CO3, solubility can be calculated as Ag2CO3⇌2Ag2S++CO32−S Ksp=(2S)2⋅S=4S3⇒S=Ksp43 S=6.2×10−1243 =1.55×10−123=1.15×10−4  For existence of Pb9IO3, there must be IO3−and Pb9+ present as constituent ions but in real Pb94− exist as ion. When we match the Ksp value of iodate of lead, we found that compound must be PbIO32.Now, we can calculate solubiliry of compound asPbIO32⇌PbS++2IO3− Ksp=S⋅(2S)2=4S3S=Ksp43=2.64×10−133 =2604×10−153 =65×10−53=4.02×10−5Hence, maximum solubility has been observed for (c), i.e.Ag2CO3