A very dilute acidic solution of Cd2+ and Ni2+ gives only yellow ppt. of CdS on passing H2S , this is due to :
a. Solubility product ( Ksp ) of CdS is more than that of NiS
b. Solubility product ( Ksp ) of CdS is less than that of NiS
c. Cd2+ belong to IIB group while Ni2+ belongs to IVth group
d. CdS is insoluble in yellow ammonium sulphide (YAS)