Correct Answer: Na2S
Reason:
The compound sodium sulfide i.e. Na2S is soluble in water. This compound gives strong alkaline aqueous solutions. On the other hand, the remaining three compounds i.e PbS, BaS and Fe2S3 are non-soluble in water. Often these compounds are also referred as sparingly soluble compounds.
We know that the heat of vaporization of water is 2260 J/g. So 100 gram sample of water being completely vaporized needs 2260*100=2.26*10^5 J. So the answer is (4).
So so sorry if i'm wrong but i'm pretty sure no
