Which of the following statements is 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 solubtions, give reddish`-` brown precipitate with mercury `(II)` chloride.
C. Sulphites in presence of zinc, reacts with dilute `H_(2)SO_(4)` to liberate `H_(2)S` gas.
D. A filter paper moistened with `KIO_(3)` and starch turns blue in contact with `SO_(2)` vapours.

Answer

2

Explanation

`(1)Cd^(2+)(aq)+H_(2)S(g)rarrCdSdarr("yellow")+2H^(+)(aq)`
`(2)Co_(3)^(2-)+4Hg^(2+)+3H_(2)OrarrHg_(4)O_(3)CO_(3)darr("reddish-brown")+6H^(+)`
`HCO_(3)^(-)(aq)` down not give precipitate.
`(3)SO_(3)^(2-)+3Zn+8H^(+)rarrH_(2)Suarr+3Zn^(2+)+3H_(2)O`
`(4)5SO_(2)+2IO_(3)^(-)+4H_(2)OrarrI_(2)+5SO_(4)^(2-)+8H^(-)`