JEE Advanced levelSingle correct optionDifficulty 3 of 3qc051
A colourless salt solution turns turbid white on dilution with water. With HX2S in dilute HCl it gives a dark brown precipitate that is insoluble in yellow ammonium sulphide. Taking the cation to be BiX3+ from 5.00g of BiClX3 (Bi 209, Cl 35.5, S 32; 2BiClX3+3HX2SBiX2SX3+6HCl), the mass of the sulphide formed on complete precipitation is
A3.31 g
B4.07 g
C2.04 g
D8.15 g
Answer: B
M(BiClX3)=209+3×35.5=315.5gmol−1, so n=5.00/315.5=0.01585mol. The equation gives n(BiX2SX3)=n/2=0.00792mol, and M(BiX2SX3)=2×209+96=514. Mass =0.00792×514=4.07g.