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 weall as bicarbonate ions in the solutions, give reddish-brown precipitate with mercury (II) chloride.
C. Sulohites 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

(b) `CO_(3)^(2-)+4Hg^(2+)+3H_(2)O rarr underset(("Reddish brown"))(3HgO.HgCO_(3))darr HCO_(3)^(-)` do not form ppt.
(c) `H_(2)S` gas is evolved.