Which of the following statements is/are incorrect ?

Options

A. A filter paper moistened with cadmium acetate solution turns yellow, when brought in contact with `H_(2)S` gas.
B. Both carbonate ions as well as bicarbonate ions in the solutions, give reddish-brown precipitate with mercury (II) chloride.
C. Sulphites in presence of zinc, reacts with dilute `H_(2)SO_(4)` to liberate `SO_(3)` gas.
D. A filter paper moistened with `KIO_(3)` and starch turns blue in contact with `SO_(2)` vapours.

Answer

B, C

Explanation

`(A) Cd^(2+) (aq) +H_(2)S (g) to CdS darr("yellow")+2H^(+)(aq)`
`(B) CO_(3)^(2-) +4Hg^(2+)+3H_(2)O to HgCO_(3).3HgO darr ("reddish-brown")+6H^(+)`
`HCO_(3^(-))(aq)` does not give precipitate.
`(C ) SO_(3)^(2-)+3Zn+8H^(+) to H_(2)S uarr +3Zn^(2+)+3H_(2)O`
`(D) 5SO_(2)+2IO_(3^(-))+4H_(2)O to I_(2)+5SO_(4)^(2-)+8H^(+)`